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REESE    LIBRARY 

OF   THE 

UNIVERSITY  OF  CALIFORNIA. 


Accessions  No.^.'?^  shelf  No. 


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Oldest   and    Largest  Paving    Company 

IN    THE 

UNITED    STATES. 

It  has,  up  to  January  i,  1890,  laid  Asphalt  Pavements  in  Twenty- 
seven  Cities  of  the  United  States,  on  607  streets,  of  a 
length  of  260  miles,  covering  an  area  of 
3,916,574  square  yards. 

No  Asphalt   Pavement  laid  by  this  company  in  the  United  States  has 
ever  been  replaced  by  another  form  of  pavement. 

This  company  has  taken  up  other  pavements,  and  replaced  them 
with  Trinidad  Asphalt  Pavements  to  the  following  extent  : 

WOOD,  459,033  sq.  yds. 

STONE,  -    451,442 

FKENCH  ROCK  ASPHALT,  27,134  " 
COAL  TAK  AND  VULCANITE,  64,219  " 
MACADAM.  -  415,686  " 

TOTAL,      -  1,417,514 

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7  x  20         "       12  to  15     "      15     " 

8  X  25      "    15  tO  20   u    20   " 
10  X  25      "    20  tO  30   "   30   " 

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ENGINEERING  NEWS 

AND 

AMERICAN    RAILWAY   JOURNAL. 


PUBLISHED    WEEKLY     BY 


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authority. 


THE 


SCIENCE  OF  ROAD  MAKING. 


BY 


CLEMENS  HEESCHEL,  M.  Am.  Soc.  C.  E. 

t  9 


CONSTRUCTION «»  MAINTENANCE 
OF  ROADS. 

BY 

EDWARD  P.  NORTH,  M.  Am.  Soc.  C.  E. 


NEW    YORK: 
ENGINEERING  NEWS   PUBLISHING  COMPANY, 

1890. 


PREFACE. 


The  science  of  roadmaking  was  revised  by  Mr.  CLEMENS  HERSCHEL 
in  1877,  and  the  paper  of  Mr.  EDWARD  P.  NORTH  was  presented  to  the 
American  Society  of  Civil  Engineers  in  1879.  To  the  one  was  awarded 
the  First  Prize  of  the  State  Board  of  Agriculture  of  Massachusetts,  and  to 
the  other  the  Norman  Gold  Medal  of  the  American  Society  of  Civil  Engi- 
neers. Though  considerable  advance  in  processes  and  machines  has 
been  made  since  these  dates,  these  two  papers  still  contain  more  con- 
densed and  valuable  information  on  a  subject  now  attracting  wide-spread 
attention  than  any  similar  publication  of  which  we  have  knowledge. 
Literature  on  the  actual  detail  of  road-making  is  scarce  and  fragmentary  ; 
and  it  is  with  the  hope  that  these  two  otherwise  practically  inaccessible 
papers  may  prove  profitable  reading  to  engineers  and  others  interested  in 
road-making  that  they  are  now  reprinted. 


TABLE  OF  CONTENTS. 


PART  I. 

INTRODUCTION 5 

LAYING  OUT  A  ROAD 6 

Considerations  which  Determine  Best  Location 6 

Roman  vs.  Modern  Road  Builders * 6 

Minimum  Radii  in  Mountainous  Districts 6 

Concerning  Grades,  Telford's  Rule 7 

Experimental  Conclusions ,  v 7 

Nomenclature  of  Roads V. 7 

Effects  of  Various  Grades  on  Amount  a  Horse  Can  Pull 8 

Width  of  Roads 9 

Actual  Field  Work  of  Laying  out  the  Road 10 

MAKING  THE  ROAD  BED  10 

Earthworks,  Data  for  Cost  of 11 

Transporting  Earth :  Shovels  and  Wheelbarrows 11 

Loosening  the  Earth  (Table) 12 

Portable  Railroad  and  Hand  Cars 13 

One-Horse  Carts 14 

Shrinkage  of  Different  Soils 14 

Drains  and  Culverts 15 

Bridges 17 

MAKING  THE  ROAD  SURFACE 17 

Foot  Paths 17 

Riding  Paths 18 

A  Good  Road  Surface 18 

Value  of  Old  Engineering  Treatises  on  Roads 19 

Experience  of  Older  Countries 19 

Chinese  Roads 19 

Macadam's  Invention 19 

Foundation,  or  Telford,  Roads 20 

Roadbuilding  in  Baden,  Germany 20 

Rules  in  Prussia  for  Inclinations , 21 

Macadam  Top 21 

Material  for  Road  Covering 22 

Crushing  Machinery 23 

Spreading  the  Material 27 

Practice  in  Bohemia 27 

Road  Rollers 27 

Literature  of  Steam  Road  Rollers 28 

Description  of  Best  Horse  Road  Roller 29 

Estimating  Cost  of  Macadam  Road 31 

Gravel  Top.    Central  Park  Roads 33 

Comparative  Cost  of  Good  and  Bad  Roads 35 


TABLE  OF  CONTENTS. 


KEEPING  ROADS  IN  REPAIR 35 

Value  of  Constant  Repairs  37 

Value  of  Annual  Repairs 37 

Tresaguet's  Method  in  Baden 37 

•Comparative  Tables  of  Cost -. 38 

How  to  Repair  Roads  on  the  Continuous  System 39 

Repairs  of  Macadamized  and  Much  Frequented  Streets  in  Cities 41 

PAVEMENTS  AND  TRACKWAYS 42 

Stone  Pavements 42 

"Wooden  Pavements 43 

Cast  Iron  Pavements 44 

Asphalte  Pavements 44 

Trackways  and  Plank  Roads  44 

ON  THE  RESISTANCE  TO  MOTION  IN  THE  FORCE  REQUIRED  TO  MOVE 

VEHICLES  ON  DIFFERENT  KINDS  OF  ROADS 45-49 

PART  II. 
BEST  METHOD  OF  SUPERINTENDING  THE  CONSTRUCTING  AND  REPAIRING 

OF  PUBLIC  ROADS 50-60 

APPENDIX. 

AN  ACT  FOR  THE  MORE  PERFECT  CONSTRUCTION  AND  MAINTENANCE  OF 
THE  COMMON  ROADS  ON  HIGHWAYS  THROUGHOUT  MASSACHU- 
SETTS   ...61-64 


THE  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS  : 

Earth  Roads 65-67 

Macadam 67-82 

Stone  Pavements ; 82-83 

Wood  Pavements 83-88 

Asphalte  and  Bitumen 88 

Compressed  Asphalte 90 

Asphaltic  Mastic 95 

Bitumen  Mastic 97 

Tar  Mastic  99 

Appendices 100 

No.  1.  Extract  from  Birmingham  (England)  Specification 100 

No.  2.  Extract  from  Specification  for  Telford,  Macadam  and  Trap 

Block  Gutters  on  Fifth  avenue,  N.  Y 100 

No.  3.  The  Gellerat  Roller 103 

The  Lindelof  Roller 104 

The  Aveling  &  Porter  Roller 104 

The  Ross  Roller 106 

No.  4.  A  Part  of  the  Contract  for  the  Construction  and  Maintenance 

of  the  Streets  and  Sidewalks  of  the  City  of  Jassy 107 

No.  5.  Abstract  of  Specifications  and  Schedule  of  Prices  for  the  Con- 
struction and  Maintenance  of  Footpaths  and  Sidewalks  in  Asphaltic 
Mastic,  and  the  Places  and  Roadways  in  Compressed  Asphalte  be- 
longing to  the  Municipal  Service  of  Paris,  from  January  1,  1878,  to 

December  31, 1882,  Paul  Crochet,  Contractor 112-117 

DISCUSSION  ON  THE  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS 119 

NOTE  ON  THE  NOMENCLATURE  OF  BITUMEN.  . .  .143 


THE  SCIENCE  OF  ROAD  MAKING. 


INTRODUCTION. 


This  treatise  was  written  in  answer  to  the  printed  circular  of  a 

Committee  of  the  Board  of  Agriculture,  calling  for  "treatises 
upon  the  science  of  road  making,  and  the  best  methods  of  superin- 
tending the  construction  and  repair  of  public  roads  in  this  Com- 
monwealth." 

This  circular  was  issued  about  the  middle  of  December,  and  as 
the  time  for  writing  and  sending  in  the  called-for  essays  was  limi- 
ted to  January  28,  the  writer  has  thought  it  best,  no  specific  char- 
acter being  prescribed  for  the  treatises,  to  attempt  to  write  one 
suitable  to  be  so  called  from  the  stand-point  of  the  public,  rather 
than  from  that  of  the  civil  engineer,  and,  giving  results  rather  than 
the  methods  of  arriving  at  them,  to  be  as  concise  as  possible. 


THE  SCIENCE  OF  ROAD  MAKING. 

Starting,  then,  with  the  first  of  the  two  subjects  mentioned  in 
the  circular, —  the  science  of  road  making,  we  can  divide  this  into 
three  periods:  I.  Laying  out  a  road  ;  2.  making  the  road-bed, 
which  includes  all  earthworks,  cutting  and  filling,  culverts,  drains, 
bridges,  even  tunnels,  etc.;  and  3.  the  making  of  the  road  surface; 

*A  First  Prize  Treatise  awarded  to  the  Author  by  the  State  Board  of  Agricul- 
ture, of  Massachusetts. 


THE  SCIENCE  OF  ROAD  MAKING. 


to  which,  not  improperly  might  be  added,  4.  keeping  the  road  in 
repair. 

LAYING  OUT  A  ROAD. 

The  considerations  which  determine  the  best  location  of  a  road, 
are  those  arising  from  the  nature  of  the  travel  it  is  proposed  to 
accommodate ;  that  is,  from  the  admissible  grades,  radii  of  curves, 
etc.  Given  two  points  it  is  desired  to  connect,  with  no  intermedi- 
ate point  where  the  road  is  to  touch,  that  route  is  the  best  which 
will  cost  least  to  build  and  maintain,  the  grades  and  curves  being 
kept  within  bounds ;  and  to  find  this  location  constitutes  the  whole 
problem  of  the  engineer.  $ 

In  older  countries,  where  trade  and  manufactures  are  more 
settled  and  unchanging  than  in  the  United  States,  the  probable 
future  travel  upon  a  road  about  to  be  laid  out  and  built,  forms  a 
material  element  in  the  data  that  govern  its  alignment  and  grades. 
A  very  able  and  clever  article  upon  this  subject  may  be  found  in  the 
Journal  of  the  Society  of  Civil  Engineers  and  Architects  at  Han- 
over," for  the  year  1869,  and  also  in  pamphlet  form.  It  is  in  the 
German  language,  written  by  Launhardt,  Superintendent  of  High- 
ways (and  a  civil  engineer)  in  the  Hanoverian  provinces. 

The  Romans  built  all  of  their  roads  in  perfectly  straight  lines, 
up  hill  and  down,  at  a  very  great  expense,  as  being  absolutely  the 
shortest  distance  between  two  points.  At  a  later  period  in  history, 
it  was  argued  that  a  road  must  be  winding  to  be  agreeable,  and 
many  were  so  built  only  for  this  reason.  The  modern  road- 
builder  or  engineer  in  general,  ignores  any  such  considerations,  and 
has  for  his  aim  only  to  achieve  the  most,  at  the  least  present  and 
future  expense.  t 

As  regards  curves  in  roads  in  a  hilly  or  mountainous  district, 
we  have  then  the  rules  never  to  make  a  smaller  radius  than  20  feet, 
and  that  only  in  extraordinary  cases.  On  roads  where  long  log- 
ging or  other  wagons  may  be  expected,  the  smallest  radius  ought 
to  be  50  or  60  feet;  and,  in  general,  40-45  feet  is  none  too  much. 

A  rule  sometimes  followed  in  constructing  mountain  roads,  is, 
where  the  inclination  is  I  or  2  in  a  hundred,!  heavy  teams  require 

\  In  describing  grades,  the  first  figure  gives  the  vertical  height  which  is  ascended 
in  a  horizontal  distance  given  by  the  second  figure.  Both  figures  must  of  course 
be  taken  to  refer  to  the  same  unit  of  length,  thas :  100  feet  in  120  feet,  100  inches 
in  120  inches,  or  100  miles  in  120  miles,  all  express  the  same  inclination  to  a  level 
plane,  and  are  more  general  in  their  application  than  the  ways  of  expressing  grades 
in  so  many  inches  to  the  foot,  or  feet  in  one  mile,  etc.,  etc. 


THE  SCIENCE  OF  ROAD  MAKING. 


.40.'  and  light  ones  30.'  radius;  with  a  grade  of  2  or  3  in  a  hundred, 
heavy  teams  require  65.'  and  light  ones  50.'  ra- 
dius. Where  a  reverse  curve  [shaped  like  the 
letter  S]  occurs,  there  should  be  a  straight  piece 
connecting  the  two  curves  [Fig. 
i.]  On  the  contrary,  where  the 
two  curves  to  be  connected  are 
concave  in  the  same  direction,  the 
FIG.  i.  connecting  link  should  be  curved 

also,  and  not  straight,  [Fig.  2.]  On  the  length 
of  the  curves  the  grade  should  be  made  easier 
than  on  the  parts  of  the  road  immediately  ad- 
Joining. 

As  regards  grades,  to  start  with  mountain  paths,  we  find  pedes- 
trians able  to  walk  up  an  inclination  of  100  in  120;  mules,  ponies, 
etc.,  100  in  173.  For  roads,  Telford's  rule  was,  that  for  horses 
attached  to  ordinary  vehicles  to  trot  up  a  hill  rising  3  in  100,  was 
equal  to  walking  up  one  of  a  5  in  a  100  grade. 
Experiments  have  shown  that-*- 

1.  On  a  road  falling  2  in  a  hundred,  vehicles  would  run  down 
of  themselves. 

2.  On  the  same  kind  of  road,  but  having  an  inclination  of  4 
in  a  hundred,  light  vehicles  had  to  be  held  back  lightly,  loaded  ones 
with  considerable  force. 

3.  On  a  road  having  a  iall  of  5^  in  a  hundred,  light  vehicles 
had  to  be  held  back  with  considerable  force,  or  if  a  brake  was 
applied  they  had  to  be  pulled,  whereas  heavy  or  loaded  vehicles 
.had  to  be  braked  to  keep  the  horses  from  being  speedily  exhausted. 

On  inclinations  steeper  than  5  in  a  hundred,  the  rainwater  run- 
ning down  the  road  is  apt  to  do  some  damage  to  the  road  surface. 

The  regulations  of  different  countries  having  a  long  experience 
in  road  building,  such  as  France,  Prussia,  Baden,  etc.,  vary  some- 
what, but  the  following  is  the  general  result : 

In  treating  of  roads,  it  often  renders  the  subject  much  clearer, 
to  divide  them  into  three  classes :  first,  second,  and  third  class  roads, 
or,  as  we  might  also  say,  state,  county  and  town  roads.  Accepting 
this  nomenclature,  we  have  this :  for  first-class  or  state  roads,  the 


8  THE  SCIENCE  OF  ROAD  MAKING. 

greatest  inclination  should  not  exceed  3-5  in  a  hundred ;  second-class 
or  county  roads,  5-7  in  a  hundred;  third-class  or  town  roads,  7-10 
in  a  hundred.  A  road  rising  10  in  a  hundred  is  not  supposed  ever 
to  have  any  heavy  teams  upon  it.  In  ascending  a  hill  it  is  well  and 
proper  to  decrease  the  grade  as  the  top  is  reached,  and  in  the  same 
measure  as  the  horses  get  tired.  Thus,  if  a  first-class  road  starts 
up  hill  with  a  grade  of  4*^  per  hundred,  it  should  gradually  dimin- 
ish to  4  and  3^  in  a  hundred,  and  end  near  the  top  with  a  grade  of 
3  in  a  hundred. 

Launhardt,  the  superintendent  of  hignways,  and  engineer,  men- 
tioned in  the  previous  note,  has  a  valuable*  article  on  the  subject 
of  the  best  grades  for  highways,  in  the  Engineering  journal  there 
mentioned,  for  the  year  1867;  re-printed  also  in  pamphlet  fornu 
He  shows  in  this  article  that,  according  to  the  received  formula 
that  expresses  the  relations  between  the  tractive  force,  the  velocity 
in  feet  per  second,  and  the  daily  working  hours  that  go  to  pro- 
duce the  maximum  amount  of  work  that  can  be  got  out  of  a 
draught-horse,  a  uniform  grade  between  any  two  points,  except 
perhaps  in  curves,  and,  if  desired,  for  resting  places,  is  the  grade  that 
tends  to  enable  the  horse  or  other  draught  animal  to  produce  the 
most  work  per  diem. 

If  a  grade  of  4  or  5  in  a  hundred  must  needs  be  kept  up  for 
some  distance,  then  it  is  well  to  have  resting  places  40  or  50  feet 
long,  having  a  grade  of  only  \^  or  two  in  a  hundred,  in  the 
line  of  the  road  at  proper  intervals.  An  expedient  adopted  by  Tel- 
ford,  the  eminent  English  engineer,  in  order  to  avoid  making  a 
piece  of  road  a  mile  long,  on  a  less  grade  than  5  in  a  hundred,  on 
account  of  the  increased  cost  this  would  have  occasioned,  and  yet 
not  have  this  part  of  the  road  too  much  more  tiresome  for  the 
horses  than  the  rest,  was  to  make  the  road-surface  on  this  mile  of  a 
much  better  quality  than  on  the  remainder;  the  additional  cost 
required  for  the  improved  road-bed  amounting  to  only  about  one- 
half  of  what  it  would  have  cost  to  reduce  the  grade  to  say  4  in  a 
hundred,  as  will  be  again  referred  to  under  the  head  of  trackways. 
In  sharp  curves  the  grade  should  be  only  i  or  2  in  a  hundred  or 
level. 

The  following  table  gives  the  effects  of  various  grades  on  the 
amount  a  horse  can  pull,  and  is  based  on  calling  the  load  a  horse 
will  pull  on  a  level,  one : — 


THE  SCIENCE  OF  ROAD  MAKING. 


9 


Then,  on  a  grade  of      100,  a  horse  can  pull 0.90 

50,  "  "          0.81 

44,  "  "          0.75 

40,  "  "          0.72 

30,  M  "           0.64 

26,  "  "          0.54 

24,  "  "          0.50 

20,  "  "          0.40- 

10,  •'  "          0.25 

To  determine  whether  it  is  most  advisable  to  go  over  or  around 
a  hill,  all  other  considerations  being  equal,  we  have  this  rule :  Call 
the  difference  between  the  distance  around  on  a  level  and  that  over 
the  hill  ,  d,  the  distance  around  being  taken  as  the  greatest,  and  call 
^,  the  height  of  the  hill. 

Then  in  case  of  a  first  class  road,  we  go  round  when  d  is  less 
than  i 6  h. 

And  in  case  of  a  second  class  road,  we  go  around  when  d  is  less 
than  10  h. 

When  the  height  of  a  necessary  embankment  gets  to  be  more 
than  60  or  65  feet,  a  bridge  or  viaduct  will  be  found  cheaper,  and 
the  same  measure,  60  feet,  applies  in  case  of  tunnels,  they  being^ 
cheaper  at  that  depth  than  open  cuttings. 

Under  the  head  of  laying  out  roads,  something  should  be  said 
of  their  width.  Speaking  only  of  such  roads  as  are  not  apt  to  turn 
into  streets  from  their  proximity  to  towns  and  cities,  it  is  well  not 
to  make  them  too  broad,  for  the  less  the  width,  the  less  the  cost  of 
construction  and  maintenance,  and  a  good  23  feet  road  is  much  bet- 
ter than  a  poor  one  40  or  more  feet  wide.  Each  rod  (16^  feet)  in 
width  adds  two  acres  per  mile  to  the  road.  An  agreeable  form  of 
road  is  to  have  on  each,  or  on  one  side  of  the  same,  a  strip  5  or  6  feet 
wide,  sodded,  and  then  a  sidewalk  equal  in  width  to  one-eighth  the 
width  of  the  roadway.  The  intervening  strip  above  mentioned,  is 
planted  with  trees  and  at  intervals  of  200-250  feet  furnishes  storage 
places,  30  or  40  long,  for  the  materials  used  in  the  road  repairs. 
The  width  of  first,  second  and  third  class  roadways  may  be  given 
as  26,  i8j£  and  13  feet,  with  a  tendency  during  the  last  ten  years 
to  have  none,  except  in  the  vicinity  of  cities,  wider  than  24  feetr 
and  the  rest  correspondingly  narrower.  In  view  of  the  changes 
constantly  going  on  in  this  country  in  the  value  and  settlement  of 


I0  THE  SCIENCE  OF  ROAD  MAKING. 

land,  it  would  probably  be  well  always  to  lay  out  a  road  50  or  60 
feet  wide,  but  to  build  the  road  proper  of  the  width  above  indi- 
cated. 

With  all  these  rules  and  data  in  mind,  the  real  work  of  actu- 
ally laying  out  the  road  on  the  ground  and  on  a  map  is  next  in 
order,  and  this  comes  so  entirely  within  the  province  of  the  civil 
engineer,  and  is  a  matter  requiring  so  much  explanation  and  study, 
that  it  cannot  well  be  introduced  within  the  limits  of  this  treatise. 
It  is  in  this  part  of  the  work  that  a  little  skill  and  labor  well  spent 
may  be  productive  of  very  great  saving  in  the  cost  of  the  whole 
work  and  it  should  not  be  left  to  the  inexperienced  or  unskilful.* 
MAKING  THE  ROAD-BED. 

Under  this  head  are  included,  earthworks,  drains,  culverts, 
bridges,  stay  walls,  etc.,  etc.,  all  matters  requiring  a  special  kind  of 
skill  to  construct  properly.  The  writer  believes  it  impracticable  to 
write  a  book  which  shall  at  once  be  interesting  to  and  therefore 
valued  by  the  public,  and  of  value  to  the  professional  man,  and 
thinks  an  attempt  so  to  do  results  always  in  a  failure  in  both  direc- 
tions. True  to  the  determination  expressed  in  the  introduction,  he 
proposes,  therefore,  to  treat  under  this  head  mainly  with  those  parts 
of  the  subject  in  which  the  public  at  large  is  most  interested,  for 
example,  the  data  for  the  cost  of  earthworks,  general  information 
relating  to  drainage,  bridges,  etc. 

*Gillespie,  in  his  treatise  on  "Roads  and  Railroads,"  gives  two  forcible 
instances  of  the  amount  those  roads  which  might  properly  be  called  chance  roads, 
«:an  be  improved  by  a  road-maker  of  skill  and  understanding.  An  old  road  in 
Anglesea,  England,  rose  and  fell,  between  its  two  extremeties,  twenty-four  miles 
apart,  a  total  perpendicular  amount  of  3,540  feet ;  while  a  new  road,  laid  out  by 
Telford  between  the  same  points,  rose  and  fell  only  2,257  feet ;  so  that  1,283  feet 
•of  perpendicular  height  is  now  done  away  with,  which  every  horse  passing  over  the 
road  had  previously  been  obliged  to  ascend  and  descend  with  its  load.  The  new 
road  is  besides  two  miles  shorter.  The  other  case  is  that  of  a  plank-road  built  in 
the  State  of  New  York,  between  the  villages  of  Cazenovia  and  Chittenango.  Both 
these  villages  are  situated  on  Chittenango  Creek,  the  former  being  eight  hundred 
feet  higher  than  the  latter.  The  most  level  common  road  between  these  villages, 
rose,  however,  more  than  1,200  feet  in  going  from  Chittenango,  to  Cazenovia, 
and  rises  more  than  four  hundred  feet  in  going  from  Cazenovia  to  Chittenango  in 
spite  of  this  latter  place  being  eight  hundred  feet  lower.  That  is,  it  rises  four  hun- 
dred feet  where  there  should  be  a  continual  descent.  The  line  of  the  plank- road 
laid  out  by  George  Geddes,  civil  engineer,  ascends  only  the  necessary  eight  hundred 
feet  in  one  direction,  and  has  no  ascents  in  the  other,  with  two  or  three  trifling 
exceptions  of  a  few  feet  in  all,  admitted  in  order  to  save  expense.  The  scenes  of 
similar  possible  improvements  are  scattered  all  over  this  and  the  rest  of  the  States ; 
and  these  facts  are  still  more  or  equally  to  be  borne  in  mind  in  laying  out  new  roads, 
where  the  ounce  of  prevention  may  take  the  place  of  the  pound  of  cure. 


THE  SCIENCE  OF  ROAD  MAKING. 


II 


EARTHWORKS. 

The  basis  of  all  values  is  the  daily  wages  of  a  common  unskilled 
laborer,  and  in  the  data  given  below,  this  figure,  whatever  it  is  from 
time  to  time  and  in  various  places,  must  be  taken  as  unity,  or  the 
standard  measure. 

The  cost  of  earthworks  may  be  divided  into  three  parts — (i)  cost 
of  loosening  the  earth,  (2)  cost  of  transport,  and  (3)  cost  of  forming 
the  transported  earth  into  the  desired  shape.  The  cost  of  the  first 
part  depends  materially  on  the  kind  of  earth  to  be  handled.  The 
cost  of  the  second,  mainly  on  the  distance  the  earth  is  to  be  moved. 

We  find  by  experience,  that  in  digging  and  loading  or  throwing 
5-10  feet  horizontally  with  a  shovel,  we  obtain  for  different  mate- 
rials the  results  of  the  table  on  the  next  page. 
TRANSPORT  OF  EARTH. 

Throwing  with  a  shovel. — This  is  to  be  done  only  from  5-12 
feet  in  distance  or  from  5-6  feet  vertically.  To  throw  5  fwet  verti- 
cally, costs  as  much  as  12  feet  horizontally,  that  is  to  say,  if  30  feet 
horizontally  cost  per  cubic  yard,  one  day's  wages  divided  by  8.4 
the  same  distance  vertically  will  cost  about  2^  times  as  much,  or 
more  exactly,  one  day's  wages  divided  by  3.5,  whence  is  seen  the 
economy  of  using  windlasses,  etc.,  instead  of  "stages,**!  in  shovel- 
ing earth  vertically.  The  table  gives  the  cost  of  shovelling  earth 
certain  distances,  expressed  in  the  number  of  cubic  yards  a  laborer's 
day's  wages  will  pay  for. 


jjil 

fllf 

DISTANCE  OF 
THROW  IN  FBET. 

M 

li 

s||| 

•Sglf 

Remark*. 

"rt 
u 

1 

|il! 

fill! 

0-10,      . 

Horizontally, 

No  "stages." 

23.5 

10-20,       . 
20-30,      . 

<« 

i  stage. 
2  stages. 

12.6 

8.4 

)   IflTheelbarrow 
r        cheaper. 

0-5,       . 

Vertically, 

No  stages. 

14.1 

5-10,     . 

" 

i  stage. 

8.8 

t  By  a  "  stage"  is  meant  the  operation  of  one  shoveller  lifting  and  throwing  what 
another  has  thrown  in  front  of  him. 


12 


THE  SCIENCE  OF  ROAD  MAKING. 


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THE  SCIENCE  OF  ROAD  MAKING. 


Wheelbarrows. — The  usual  distance  of  transport  suitable  for  the 
use  of  wheelbarrows  is  100-200  feet.  In  exceptional  cases  it  maybe 
more,  but  perhaps  never  above  500  feet  and  then  only  for  mode- 
rate quantities.  In  going  up  hill,  the  greatest  inclination  is  to  be  not 
more  than  i  in  10,  and  a  man  can  push  only  ^  as  much  on  this  in- 
clination as  on  a  level.  3  feet  vertical  transport  costs  as  much  as 
90-100'  horizontally.  Whenever  possible,  planks  should  be  laid  for 
the  wheel-barrows  to  run  on.  The  best  timber  for  this  purpose  is 
beechwood  and  the  cost  of  keeping  such  planks  is  only  about  -fa  or 
-^5-  per.  cent,  of  the  cost  of  transport  per  cubic  yard. 


gg'SS 

0.3  c  o 

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Distance  of  Transport  in  Feet. 

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10-20,           

120 

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23.5 

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16.0 

50-70  

100 

14.4 

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06 

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150-200  

94 

12.8 

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12.  0 

88 

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II    6 

86 

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II.  2 

400-450  

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10.9 

82 

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500-550,           

80 

2K 

IO.2 

PATENT  PORTABLE  RAILROAD  AND  HAND-CARS. 
These  have  lately  been  introduced  in  this  country,  and  appear  to 
be  coming  into  general  use  and  favor.  The  company  owning  this 
improvement,  as  it  seems  to  have  a  right  to  be  called,  claim,  that  by 
means  of  their  track  and  cars,  which  can  be  used  everywhere  that  a 
wheel-barrow  or  a  horse-cart  can  go,  and  in  a  great  many  places 
where  these  vehicles  cannot  go,  they  affect  a  very  large  saving,  as 
much  in  some  cases  as  £  of  the  cost  by  the  other  means  of  transport. 
There  are  no  data  published  as  yet  to  make  tables  from,  similar 
to  the  foregoing ;  from  the  company's  pamphlet,  however,  one  given 
case  which  occured  on  Staten  Island  in  1867,  may  be  analyzed  and 
tabulated  as  follows: — 


THE  SCIENCE  OF  ROAD  MAKING. 


Distance  of  transport,  in  feet,  . 

Number  of  trips  per  day  often  hours,  with  one  man  at 

two  cars,  and  two  to  load,  .  .  .  .  . 
Contents  of  car  in  cubic  feet,  .  .  .  .  . 

Number  of  cubic  yards  which  can  be  transported  at  the 

cost  of  one  laborer's  day's  wages,  .... 

ONE-HORSE  CARTS. 

The  table  for  this  kind  of  transport  may  be  stated  about 
lows.     i  foot  vertical  costs  as  much  as  14  horizontal. 


150 
11.34 

60 

as  fol- 


•s ill  £ 

1 

lilt 

•^  jj1""1  « 

ti^t 

.y  -b  w"0 

S.S  §  5  A 

s« 

"s^^S--* 

Distance  of  Transport  in  feet. 

'*%%»% 

5 

'Sgrto  . 

*o|||g 

is 

flj 

*  fri  !3  P  ^H 

s  s 

"*"*   fe 

^^ 

5 

» 

86 

8 

17.  1 

67 

8 

13  6 

A* 

8 

8  6 

1,500,          .        .        *  ...   -  fc 

31 

8 

6.4 

2C 

8 

50 

21 

8 

4<5 

18 

8 

i  6 

Ox-cart  transport  is  10  or  12  per  cent,  cheaper  than  the  above,  but 
takes  more  time. 

Other  methods  of  transport,  such  as  horses  or  engines  on  tem- 
porary tracks,  would  hardly  ever  be  applied  to  road-building,  but 
belong  more  properly  under  the  head  of  railroad  construction. 

,  SHRINKAGE. 

In  calculating  the  cost  of  earthworks,  the  so-called  shrinkage  of 
earth  must  not  be  overlooked.  Earth  occupies  on  the  average  ^ 
less  space  in  embankment  than  it  did  in  its  natural  state,  100  cubic 
yards,  shrinking  into  90.  Rock  on  the  contrary,  occupies  more 
space  when  broken,  its  bulk  increasing  by  about  one-half. 

The  shrinkage  of  gravelly  earth  and  sand  may  be  taken  at  8,  of 
clay  10,  loam  12,  surface  soil  15,  and  of  "puddled  "  clay  25  percent. 
The  increase  of  bulk  of  rock  is  40  to  60  per  cent. 


THE  SCIENCE  OF  ROAD  MAKING. 


To  make  use  of  all  these  data  in  calculating  the  probable  cost  of  a 
piece  of  road,  there  are  of  course  still  wanting  the  equally  essential 
factors  which  give  the  number  of  cubic  yards  to  be  dug  and  moved 
and  the  distance  of  transport.  These  are  got  from  the  plan,  profile 
and  cross-sections  of  the  proposed  work,  an  engineer's  knowledge 
being  requisite  to  make  the  necessary  drawings  and  calculations. 

DRAINS  AND   CULVERTS. 

The  drainage  of  roads  is  of  two  kinds,  surface  and  sub-drain- 
age. The  first  provides  for  a  speedy  removal  of  the  rain-fall  on 
the  surface  of  the  road  and  the  cutting  and  embankments  on  which 
it  is  carried;  the  second,  for  the  removal  of  that  part  of  the  rain- 
fall which  nevertheless  does  penetrate  into  the  body  of  the  road- 
covering.  With  a  perfect  sub-drainage  the  winter's  frost,  having  no 
water  to  act  upon  within  the  body  of  the  road,  is  robbed  of  its  great 
power  to  destroy  the  same,  and  it  also  prevents  the  road-surface  from 
becoming  soaked  and  thence  destroyed  in  the  summer.  The  need 
of  surface  drainage  is  self-evident.  This  last  named  is  to  be  pro- 
vided for  at  this  stage  of  the  building  of  the  road,  the  sub-drainage  be- 
ing more  properly  a  part  of  the  building  of  the  road-covering  or  top. 
For  this  purpose  ditches,  one  on  each  side  generally,  are  absolutely 
necessary,  both  when  the  road  is  on  a  level  with  the  surrounding 
country  and  when  it  is  in  a  cutting.  They  may  become  necessary 
also  in  the  case  of  embankments :  for  example,  when  an  embankment 
is  built  across  wet  ground.  Where  these  side  ditches  cross  under 
the  embankment  we  have  a  culvert :  also  whenever  any  small  valley, 
having  a  constant  or  intermittent  stream  of  water,  is  crossed  by  such 
an  embankment.  It  is  very  bad  policy  to  make  such  culverts  of 
wood,  unless  indeed  they  are  so  situated  as  to  be  constantly  under 
water;  the  cost  of  replacing  them  after  the  embankment  and  road 
has  been  built  over  them  is  disproportionately  great.  They  should 
be  made  of  stone,  or  brick;  lately  vitrified  stone-ware,  or  cement 
drain-pipe,  oval  or  egg-shaped,  has  been  used  to  advantage  in  their 
construction. 

All  ditches,  drains  and  culverts  should  have  a  fall  throughout 
their  entire  length.  Their  size  will  depend  on  the  amount  of  water 
they  may  be  expected  to  carry,  and  this  again  on  the  rain-fall  that 
may  occur  on  the  area  which  they  drain.  Extraordinary  showers 


16  THE  SCIENCE  OF  ROAD  MAKING. 

have  occurred  of  2  inches  in  half  an  hour  but  only  over  a  very  limited 
area,  and  2  inches  in  an  hour  may  be  taken  as  a  large  allowance. 
This  is  the  basis  of  the  Central  Park  drainage  calculations,  and  is 
•larger  than  usually  taken,  none  too  large  however  for  safety. 

The  determination  of  the  proper  width  and  height  of  culverts, 
that  will  enable  them  to  pass  the  requisite  quantity  of  water  with- 
out damming  it  up,  is  a  question  in  practical  hydraulics,  easily  enough 
settled,  in  cases  of  doubt,  by  the  proper  gaugings  and  observations 
made  upon  the  spot,  but  which  is  answered  only  in  a  very  crude 
and  imperfect  manner  by  any  general  rules  that  may  be  given. 
And  yet  it  may  prove  a  very  important  question  at  times.  There 
is  now  (1877)  pending  in  Massachusetts,  a  suit  for  damages,  that  may 
involve  claims  to  the  amount  of  rising  half  a  million  dollars,  in  which 
one  great  centre  of  attraction  is  nothing  but  a  simple  railroad  culvert, 
and  the  question :  Was  it  as  large  as  it  ought  to  have  been  ?  and  the 
writer  passes  every  day,  when  at  home,  by  a  culvert,  which  for  some 
150  or  200  years  has  dammed  the  waters  of  a  brook  back  about  3 
.miles,  from  I  ft.  to  say  20  in.  at  the  culvert  vertically,  and  done  this 
•  right  along  two  or  three  times  per  annum,  and  at  the  present  time 
it  contributes  in  this  manner,  more  than  its  proper  share  towards  the 
ilooding  of  about  500  cellars.  These  two  cases  may  serve  to  call 
.attention  to  the  great  damage  that  may  accrue  from  making  culverts 
too  small,  and  to  show  whence  comes  the  rule :  in  cases  of  doubt, 
-make  the  culvert  plenty  large  enough.  The  following  rough  anct 
approximate  rules  for  determining  the  quantity  of  water  that  a  cul- 
vert will  be  called  upon  to  pass  through  it,  are  taken  from  a  Ger- 
man pocket-book  for  road  engineers.  Compute  the  cubic  feet  pel 
second  from  the  drainage  area  that  lies  above  the  culvert,  and,  foi 
'the  different  lengths  of  valley  from  the  corresponding  rain-falls 
per  hour.  (The  rain-fall  is  given  in  inches  per  hour,  instead  of  in 
decimals  of  a  foot  per  second,  only  for  the  purpose  of  avoiding  the, 
printing  of  long  decimals). 

LENGTH  OF  VALLEY  IN  MILES.  INCHES  PER  HOUR. 

2. 5  or  less,  1.2 

2. 5  to  5.  0.75 

5-    "  7-5  0.45 

7.5  "10.  0.30 

10.  or  more,  0.15 

As  culverts  grow  larger  and  wider  with  the  amount  of  water  they 
•are  to  pass  under  the  road,  they  develope  finally  into 

BRIDGES. 

Bridge-building  is  a  life's  study,  taken  by  itself,  and  in  some  of 
its  parts  it  is  not  half  appreciated  and  known  as  yet  among  the  pub- 
lic. Prominent  among  these  is  beauty  of  design  and  appropriate- 
ness  u>  the  situation.  There  is  perhaps  nothing  else  that  will  so 


THE  SCIENCE  OF  ROAD  MAKING. 


much  improve  the  appearance  and  attractiveness  of  a  road  as  a 
beautiful  bridge.  So  also  in  cities  we  find  that  a  street  will  of  its 
own  accord,  seemingly,  improve  in  appearance,  when  a  good  and 
handsome  bridge  has  been  erected  on  its  line,  the  owners  and  build- 
ers of  the  adjoining  buildings  taking  the  bridge  for  their  pattern  and 
model.  Nor  must  it  be  supposed  that  a  handsome  bridge  must  ne- 
cessarily cost  more  than  an  inappropriate  or  homely,  uncouth  struct- 
ure ;  it  need  never  be  the  case.  Very  often  the  chief  beauty  of  a  struct- 
ure lies  in  the  fact  of  its  carrying  the  most  with  the  least  expenditure  of 
material.  No  one  bridge  is  proper  in  every  situation,  and  herein 
many  mistakes  are  made.  The  correct  way  to  build  a  good  bridge, 
is  the  same  or  a  similar  way  to  that  followed  in  first-class  buildings, 
namely,  to  have  plans  drawn  for  the  same  and  receive  estimates 
and  offers  to  build  according  to  these  plans.  It  is  not  well  to  allow 
the  offices  of  designer,  superintendent  and  contractor  to  be  united  in 
one  person  or  firm,  and  is  expecting  too  much  from  human  nature. 
MAKING  THE  ROAD  SURFACE. 

There  are  two  subordinate  kinds  of  road  surface,  if  the  term  road 
can  properly  be  applied  to  them,  namely,  that  of  foot  and  riding 
paths ;  these  may  be  disposed  of  first,  before  proceeding  to  the  more 
important  consideration  of  the  road  surfaces  proper,  those  used  by 
vehicles  of  all  descriptions. 

Footpaths. — For  the  surface  of  a  foot  path  little  solidity  is  ne- 
cessary, except  in  city  sidewalks,  which  are  not  supposed  fo  be  treat- 
ed of  here,  but  we  do  need  a  material  that  shall  become  and  stay 
compact  soon  after  it  is  laid.  Coarse  sand,  screened  gravel,  stone 
chips  and  dust,  make  good  paths ;  should  these  materials  be  too  free 
from  any  earth  or  clay,  a  little  of  the  same  may  often  be  added  to 
advantage  to  act  as  a  binding  material.  Wherever  the  ground  un- 
derneath the  surfacing  is  not  porous  or  likely  to  remain  porous 
enough  to  let  all  the  water  that  may  soak  through  drain  away,  a 
layer  of  such  porous  material  must  be  filled  up  before  the  top  sur- 
face is  put  on.  Oyster  shells,  or  large  stone  chips,  gravel  stones 
or  pebbles,  etc.,  make  a  good  foundation  of  this  sort.  The  top  cover- 
ing should  have  a  slope,  best  in  both  directions  from  the  centre  of 
the  path  towards  each  side  of  about  i  in  16;  the  thickness  of  the 
foundation  course  to  be  3  to  5,  and  that  of  the  top  3  to  4  inches. 


1 8  THE  SCIENCE  OF  ROAD  MAKING. 

No  gravel  path,  or  side-walk,  will  afford  good  walking  at  the 
season  of  the  year  when  the  frost  is  coming  out  of  the  ground. 
Carting  on  more  gravel  is  in  vain;  it  is  often  no  better  than  mere 
foolishness.  If  village  communities  will  get  this  idea  firmly  into 
their  minds,  and,  instead  of  a  fruitless  struggle  against  the  laws  of 
nature  and  of  gravel,  will  build  stone  screening  sidewalks  with  a 
good  foundation  course  underneath,  as  above  described,  or  else  some 
sort  of  hard  sidewalk  covering,  they  will  save  themselves  much  ex- 
pense, many  muddy  feet,  and  no  small  amount  of  consequent  and 
annual  discontent,  not  to  say  profanity  and  ill  feeling. 

Heavy  rolling  and  wetting  down  will  save  much  time  in  finish- 
ing the  whole  process ;  the  roller  should  be  used  unsparingly  and 
throughout  the  whole  construction  of  the  path,  on  the  foundation, 
as  well  as  on  the  top. 

Riding -Paths. — From  the  nature  of  the  travel  these  are  intend- 
ed to  acommodate,  their  surface  must  be  of  a  peculiar  kind.  Inas- 
much as  a  horse,  in  galloping,  tends  to  throw  the  soil  he  treads  on 
backwards  with  his  hoofs,  the  surface  must  be  kept  somewhat 
loose  and  soft  to  make  riding  on  it  easy  and  agreeable. 

This  requirement  makes  it  impossible  to  have  any  slope  on  the 
surface  (the  loose  material  would  wash  away  if  there  were  any),  and 
hence  we  must  rely  here  wholly  on  sub-drainage,  and  not  attempt 
any  surface  drainage.  The  top  is  made  of  coarse  sand,  free  from 
clay  or  other  binding  material,  laid  on  two  and  one-half  to  three 
and  one-half  inches  thick,  and  spread  out  level.  Under  this  is  a 
solid  foundation,  about  four  inches  thick,  made  of  coarse  gravel  and 
clay,  and  having  a  slope  of  about  1 : 20,  so  that  the  water  will  run 
off  along  its  top  surface  to  either  side,  where  it  must  further  be  dis- 
posed of  by  drains  or  ditches.  In  case  of  riding  paths  too  wide  to  be 
so  simply  built,  the  sketch  shows  the  method  to  be  used.  The 


foundation  is  made  in  several  slopes,  at  the  lowest  parts  of  which 
are  placed  drains,  running  in  the  direction  of  the  path,  but  commu- 
nicating from  time  to  time  with  the  sides  of  ditches  or  drains. 
Should,  however,  the  ground  underneath  be  porous  enough,  the 
drains  may  be  dispensed  with ;  and  if  in  their  stead  holes  be  dug 
along  the  lowest  lines,  marked  0,  #,  and  these  filled  with  large 
stone,  the  water  will,  through  them,  drain  away  into  the  ground. 
Roads. — To  make  a  good  road  surface  is  a  very  simple  operation 


THE  SCIENCE  OF  ROAD  MAKING. 


after  it  is  only  once  understood,  and,  the  fundamental  principles 
thereof  once  comprehended,  they  can  hardly  be  forgotten.  Every- 
thing connected  with  the  construction,  the  use  and  maintenance  of 
roads,  was,  in  times  past,  before  the  invention  of  railways,  the  sub- 
ject of  exact  observations  and  experiments,  many  and  varied  in  char- 
acter. 

Old  engineering  works  that  treat  of  road-making  are  on  this 
account  excellent  reading  upon  this  subject  at  the  present  day. 
Upon  road  construction  no  less  than  upon  the  need  of  better  road- 
legislation.  Some,  perhaps  the  most  of  the  evils  we  suffer,  in  the 
shape  of  bad  common  roads,  are  merely  the  result,  the  necessary 
consequence  of  our  bad  systems  of  common  road  management, 
which  are  derived  from  our  antiquated  legislation  upon  that  sub- 
ject. Legislation  of  thiskind  has  changed  but  little  in  a  hundred 
years,  and  is  producing  the  same  evils  to-day,  that  it  did  a  hundred 
years  ago.  Hence  it  is  explainable,  that  the  complaints  concerning 
bad  roads,  and  bad  road  management  which  we  read  in  books  of 
fifty  and  of  sixty  years  ago,  sound  to  our  astonished  ears  as  though 
they  had  been  written  but  yesterday.  On  this  subject  may  be 
consulted:  The  life  of  Telford,  the  great  English  road  builder, 
who  died  some  fifty  years  ago,  (also  among  "  The  Lives  of  the 
Engineers,"  by  Samuel  Smiles),  "  A  treatise  on  Roads,"  by  Sir  H. 
Parnell,  1833,  and  other  works  of  former  date. 

Besides  this,  we  have  the  results  of  a  great  number  of  years  of 
experience  in  older  countries,  and  there  would  seem  to  be  little  to 
invent,  but  much  to  learn,  in  this  branch  of  construction.  Though 
less  progressive  than  other  branches,  there  are  nevertheless  im- 
provements in  road-making,  especially  in  road-making  machinery 
and  tools;  and  no  treatise  on  this  or  any  other  living  subject  can  be 
considered  complete  in  a  very  few  years  after  it  is  written. 

Ancient  roads  were  made  with  a  surface  as  nearly  resembling  the 
solid  rock  as  possible.  So,  in  China,  roads  were  made  of  huge 
granite-blocks  laid  on  immovable  foundations.  In  time  these  be- 
came worn  with  ruts,  especially  in  the  joints  or  seams  of  the  stones, 
and  the  surface  generally  so  smooth  that  animals  could  hardly 
stand,  far  less  trot  on  it.  They  are  now  for  the  most  part  deserted, 
and  left  to  be  covered  by  land-slides,  etc.,  to  one  side  of  the  new 
roads  of  travel. 

The  invention  of  McAdam  consisted  in  having  no  large  stone  at 
all  on  the  roadway,  but  having  it  all  pounded  into  fragments  and 
spread  over  the  road-bed.  This  has,  without  fear  of  efficient  con- 
tradiction or  shadow  of  doubt,  been  proved  by  trial  to  be  a  worth- 


20  THE  SCIENCE  OF  ROAD  MAKING, 

less  proceeding,  though  at  one  time  popular,  and  eve«  now  too 
often  done,  either  from  ignorance  or  laziness.  The  separate  frag- 
ments of  stone,  have  no  bond  among  themselves,  are  liable  *c-  sink 
into  the  underlying  ground  or  road-bed,  evenly  or  unevenly  as  v 
may  chance,  more  in  one  place  than  another,  and  thus  never  come 
to  rest  or  to  an  even  top  surface.  Between  these  two  extremes  of 
an  ancient  Chinese  solid  rock  road  and  that  of  McAdam,  lies  the 
true  principle  of  road-making,  which  consists  in  giving  every  road 
two  component  parts ;  one, — the  foundation, — to  be  solid,  unyield- 
ing, porous,  and  of  large  material;  the  other— the  top  surface — to 
be  made  up  of  lighter  material,  and  to  be  made  to  bind  compactly 
and  evenly  over  the  rough  foundation.  This  constitutes  the  whole 
principle  to  be  followed;  and  let  it  be  repeated,  that  to  dump  the 
road  material  directly  on  the  ground,  without  first  preparing  a 
foundation  for  it,  as  is  so  frequently  done,  is  a  waste  of  time,  labor 
and  materials,  by  no  possibility  resulting  in  a  good  road.  On  this 
one  fundamental  idea,  which  is  never  abandoned,  however,  there 
are  a  number  of  variations.  Besides  these  roads,  whose  character- 
istic is  the  foundation  they  are  all  built  on,  we  have  paved  roads,  or 
pavements,  of  a  great  many  kinds,  and  roads  with  trackways,  also 
of  various  kinds. 

FOUNDATION  ROADS. 

The  roads  of  this  kind,  with  macadam  for  the  top  surface,  are 
called  Telford  roads  by  English  writers,  from  Telford,  who  first 
built  them  in  England.  The  Central  Park  "  gravel  roads  "  belong 
under  this  head,  gravel  taking  the  place  of  the  macadam  of  the  Tel- 
ford roads.  These  foundation  roads  are  of  far  greater  importance 
than  any  other  kind  for  State,  county  or  town  roads,  also  for  parks 
and  driveways.  The  top  surface  of  all  these  roads  must  have  a 
certain  inclination,  to  cause  efficient  surface  drainage.  Various 
authorities  give  various  rules  for  the  amount  of  this  inclination  or 
side-slope.  It  would  seem  just  that  it  should  depend  on  the  nature 
of  the  top  covering,  being  less  for  more  solid  than  for  looser  or 
softer  materials,  and  also  on  the  grade  of  the  road. 

In  Baden,  one  of  the  smaller  German  States,  but  which  is 
worthy  to  be  taken  as  a  model  in  matters  of  road-building,  and  in 
France,  the  rise  at  the  centre  is  given  as  J^-^V  °^  *^e  width  of  the 


THE  SCIENCE  OF  ROAD  MAKING.  21 

+  m**——~  i.  .•  i  .-  -i  .  — .•—••—,—— .1     ,    .        ...  .n  .  n.      .1  — .^^•i    •  ._ — „ 

raad,  according  to  the  nature  of  the  material;  that  is,  inclinations  of 
I  in  20,  and  i  in  30.  The  rules  in  Prussia  prescribe  inclinations  of 
i  in  24  for  roads  falling  more  than  4  in  a  hundred;  i  in  18  for  roads 
on  a  grade  of  between  2  and  4  in  a  hundred;  and  i  in  12  for  those 
on  a  grade  of  less  than  2  in  a  hundred.  When  first  built,  the  cen- 
tre should  be  made  some  four  inches  too  high,  to  allow  for  after 
settling. 

Macadam   Top.  —  The  cross-section  of  such  a  road  is  about  as 

drawn;     "Hl---—^^  the 

thickness  of  the  foundation  6= a,  the  thickness  of  the  top  covering 
at  the  centre,  and  is  six,  four  or  five  and  three  and  one-half  inches 
in  thickness  for  first,  second  and  third  class  roads.  If  the  stone  for 
the  foundation — for  which  most  anything  will  do,  and  that  kind 
should  be  taken  which  is  cheapest  to  procure — happens  to  be  got 
out  cheapest  in  larger  pieces  than  the  above  dimensions,  it  will  do 
no  harm.  This  foundation  course  is  sometimes  set  so  as  to  present 
an  inclination  on  top,  and  the  cover  then  put  on  of  a  uniform  thick- 
ness over  the  whole  breadth.  This  is  perhaps  best,  but  is  some- 
what more  expensive.  It  will  do,  in  nearly  all  cases,  to  set  the 
foundation  course  on  a  level,  or  as  near  so  as  the  stones  will  allow, 
»nd  then  make  the  top  crowning,  by  making  the  covering  say 
three-quarters  of  an  inch  or  an  inch  less  thick  at  the  edges  than  in 
the  centre.  The  stones  forming  the  foundation  should  not  be  set 
in  rows,  nor  ever  laid  on  their  flat  sides,  but  set  up  on  edge  and 
made  to  break  joints  as  much  as  possible;  that  is, set  up  irregularly. 
After  they  are  set  up,  the  points  that  project  above  the  general  level 
may  be  broken  off,  and  the  interstices  generally  filled  with  small 
stone.  More  or  less  care  and  work  are  necessary  in  this  part  of 
the  operation,  according  to  the  importance  of  the  road  and  the 
depth  and  character  of  the  material  used  for  the  top  covering.  To 
roll  the  road  at  this  stage  is  to  be  recommended;  afterwards  it  be- 
comes a  requisite.  The  point  never  to  be  lost  sight  of,  is  that  this 
foundation  course  must  remain  porous,  must  be  pervious  to  water, 
so  that  all  rain-water  that  shall  soak  through  the  top  covering  will 
find,  through  it,  means  of  escape  to  the  ground  underneath ;  thence, 
according  to  the  nature  of  the  subsoil,  it  is  left  either  to  soak  into 
the  ground,  or  must  be  further  led  away  by  appropriate  drains. 


23  THE  SCIENCE  OF  ROAD  MAKING. 

Of  very  great  importance  is  the  material  used  for  the  top  of 
road  covering.  In  the  order  of  their  value  for  macadam,  we  have. 

I.  Basalt. 
II.  Syenite  and  Granite. 

III.  Limestones. 

IV.  Sandstones. 

It  will  be  evident,  that  a  much  greater  quantity  of  the  soft 
stones  would  be  required  to  repair  a  certain  road,  than  of  a  harder 
kind,  and  on  a  road  lying  out  of  the  way  of  a  hard  stone  quarry  or 
deposit,  the  question  will  arise  which  is  cheapest,  to  pay  more  for 
the  raw  material  and  get  good  stock,  or  pay  less  and  use  the 
worse?  There  have  been  some  interesting  results  in  places  where 
this  matter  has  been  the  subject  of  experiment,  continued  for  a 
number  of  years.  Thus,  on  a  road  in  Baden  which  was  formerly 
macadamized  with  rock  costing  only  fifty  cents  per  cubic  yard,  it 

FIG.  5.    PERSPECTIVE  VIEW  OF  NEW  PATTERN  CRUSHER. 


was  finally  found  cheaper,  to  take  harder  rock  from  a  distarot 
costing  one  dollar  and  seventy-eight  cents  per  cubic  yard,  the  s&v- 
ing  being  both  in  less  quantity  of  material  used  and  less  labor  in- 
quired in  repairs.  Just  where  the  limit  is,  must  be  found  in  each 


THE  SCIENCE  OF  ROAD  MAKING. 


23 


case  by  long  continued  experiment,  which  is  well  worth  the  trouble 
to  make,  both  to  save  expense  and  also  to  have  the  best  possible 
road,  the  harder  material  making  a  road  better  at  all  times,  at  the 
same  or  less  cost.  After  the  right  kind  has  been  determined,  none 
other  should  be  mixed  with  it,  and  should  any  inferior  piece  acci- 
dentally or  designedly  get  into  the  stock  to  be  broken  up,  it  should 
be  picked  out  and  thrown  aside.  The  stone  is  broken  up  into 
macadam,  either  by  hand  or  machinery.  Wherever  any  consider- 
able quantity  of  macadam  is  in  present  or  future  demand,  a  stone- 
breaker  is  certainly  a  saving  over  hand-labor,  though  it  is  difficult 
to  draw  a  line  exactly,  where  hand-labor  or  machine  labor  is 
cheapest.  Probably  no  town  that  pretends  to  keep  thirty  or  forty 
miles  of  road  in  good  repair,  ought  to  be  without  one  of  these  labor- 
saving  machines.  Those  most  in  use  are  made  by  the  Blake  Crusher 
Co.,  of  New  Haven,  Conn.,  and  the  following  is  taken  from  their 
circular. 

Their  machine  has  been  patented  in  the  United  States  and  in 
several  foreign  countries,  and  is  now  in  use  in  almost  every  coun- 
try on  the  globe.  It  is  simple  and  compact,  and  being  complete  in 
itself,  requires  no  extraneous  support  or  fixtures.  Two  patterns  of 
the  machine  are  now  sold :  the  old,  or  "  Lever  Pattern,"  and  the 
new,  or  "  Eccentric  Pattern."  The  figures,  and  following  descrip- 
tion, refer  to  the  last  named  machine.  Fig.  5,  is  a  perspective  view 
of  the  machine,  entire.  The  frame  which  receives  and  supports  all 
the  other  parts,  is  cast  in  one  piece,  with  feet  to  stand  on  the  floor  or 
on  timbers.  These  feet  are  provided  with  holes  for  bolts,  by  which 
it  may  be  fastened  down  if  desired ;  but  this  is  unnecessary,  as  its 
own  weight  gives  it  all  the  stability  it  requires.  The  flywheels 
are  on  a  shaft  which  has  its  bearings  on  the  frame,  and  which  be- 
tween these  bearings,  is  formed  into  a  short  crank.  On  the  same 
shaft  is  a  pulley,  to  receive  a  belt  from  a  steam-engine  or  other 
driver. 

Figure  6  shows  a  side  view  or  elevation  of  the  parts  in  the 
machine  in  place  as  they  are  presented  to  view  through  the  side 
of  the  frame.  The  circle  D,  is  a  section  of  the  fly-wheel  shaft, 
which  should  make  from  225  to  250  revolutions  per  minute. 
The  circle  around  D  is  a  section  of  the  eccentric.  F  is  a  pit- 


THE  SCIENCE  OF  ROAD  MAKING. 


man  or  connecting  rod,  which  connects  the  eccentric  with  the  tog- 
gles G,  G,  which  have  their  bearings,  forming  an  elbow  or  toggle 
joint.  H,  is  the  fixed  jaw;  this  is  bedded  in  zinc  against  the 
ends  of  the  frame  i^  inch  thick.  P,  P,  are  chilled  plates  against 
which  the  stone  is  crushed;  when  worn  at  the  lower  end  they  can 
be  inverted,  and  thus  present  a  new  wearing  surface.  The  cheeks 
I,  I,  fit  in  recesses  on  each  side,  and  hold  the  plates  in  place;  by 
changing  the  position  of  the  cheeks  from  right  to  left,  when  wornr 
both  will  have  a  new  surface.  J,  is  the  movable  jaw;  this  is  sup- 
ported round  the  bar  of  iron  K,  which  passes  freely  through  it,  and 
forms  the  pivot  upon  which  it  vibrates.  L,  is  a  spring  of  India 
rubber,  which  is  compressed  by  the  forward  movement  of  the  jaw, 

FIG.  6.    SECTIONAL  VIEW  OF  NEW  PATTERN  CRUSHER,  WITH  PARTS  LETTERED* 
FOR  CONVENIENCE  IN  DESIGNATING  PIECES  WANTED  FOR  REPAIRS. 


and  aids  its  return.  M,  M,  are  bolt  holes.  B,  is  the  fly  wheel.  Cy 
is  the  driving  pulley.  Every  revolution  of  the  crank  causes  the 
lower  end  of  the  movable  jaw  to  advance  towards  the  fixed  jaw 
about  one-fourth  of  an  inch  and  return.  Hence,  if  a  stone  be 
dropped  in  between  the  convergent  faces  of  the  jaws,  it  will  be 
broken  by  the  next  succeeding  bite;  the  resulting  fragments  will 
then  fall  lower  down  and  be  broken  again,  and  so  on  until  they 
are  made  small  enough  to  pass  out  at  the  bottom.  The  readi- 
ness with  which  the  hardest  stones  yield  at  once  to  the  influence  of 
this  gentle  and  quiet  movement,  and  melt  down  into  small  frag- 


THE  SCIENCE  OF  ROAD  MAKING. 


ments,  surprises  and  astonishes  every  one  who  witnesses  the  opera- 
tion of  the  machine. 

It  will  be  seen  that  the  distance  between  the  jaws  at  the  bottom 
limits  the  size  of  the  fragments  This  distance,  and  consequently 
the  size  of  the  fragments,  may  be  regulated  at  pleasure.  A  varia- 
tion to  the  extent  of  -|ths  of  an  inch  may  be  made  by  turning  the 
screw-nut  W,  which  raises  or  lowers  the  wedge  N,  and  moves  the 
toggle-block  O  forward  or  back.  Further  variations  may  be  made 
by  substituting  for  the  toggles  G,  G,  or  either  of  them,  others  that 
are  longer  or  shorter;  extra  toggles  of  different  lengths  being  fur- 
nished for  this  purpose. 

This  machine  may  be  made  of  any  size.  The  builders  have  pat- 
terns for  some  13  different  sizes  on  hand  at  the  present  day.  Each 
size  will  break  any  stone,  one  end  of  which  can  be  entered  into  the 
opening  between  the  jaws  at  the  top.  The  size  of  the  machine  is 
designed  by  the  size  of  this  opening ;  thus,  if  the  width  of  the  jaws 
be  ten  inches,  and  the  distance  between  them  at  the  top  five  inches, 
we  call  the  size  10x5.  The  following  table  shows  the  principle 
facts  that  relate  to  the  sizes  of  machines  that  are  used,  generally, 
for  the  making  of  road-metal. 


I 

>H 

*j 

1  : 

Extreme  Dimensions. 

Driving  Pulley. 

-s 
& 

L 

,L 

NJ. 

M  >  .*i 

JJ 

|1| 

ll 

I 

1 

0) 

! 

4)  '3 

F 

III 

s 

a 

H 

Length 

Bre'dth 

Height. 

Diam. 

Face. 

§ 

Inches. 

ft.    in. 

ft.     in. 

ft.     in. 

ft.    in. 

inch. 

2 

10X7 

Five. 

4339 

8000 

51  lx£ 
O  /2 

3  8 

4   5 

2      0 

11A 

250 

6 

$900 

*3 

15X5 

Six. 

4700 

9100 

8  7 

5  o 

5  o 

2      4 

8 

1  80 

9 

1035 

*4 

15X7 

Six. 

5890 

10490 

8  7 

5  o 

5  o 

2      4 

9 

1  80 

9 

1125 

5 

15X9 

Seven. 

6436 

13360 

6  5 

5  o 

5  ii 

2      6 

9 

250 

9 

1234 

NOTE. — The  amount  of  product  depends  on  the  distance  the  jaws  are  set  apart,  and  the 
speed.  The  product  given  in  the  Table  is  due  when  the  jaws  are  set  i  i-a  inches  open  at  thy 
bottom,  and  the  machine  is  run  at  its  proper  speed  and  diligently  fed.  But  it  will  also  vary 
somewhat  with  the  character  of  the  stone.  Hard  stone  or  ore  tnat  breaks  with  a  snap  will  ga 
through  faster  than  Sand  stone. 

To  make  good  road  metal  from  hard  compact  stone,  the  jaws 
should  be  set  from  15^  to  i^  inches  apart  at  the  bottom.  For 
softer  and  for  granular  stones  they  may  be  set  wider. 


26  THE  SCIENCE  OF  ROAD  MAKING. 

A  cubic  yard  of  stone  is  about  one  and  one-third  tons. 

In  getting  an  engine  to  drive  one  of  these  Crushers,  it  is  ad- 
visable to  have  one  of  greater  power  than  just  what  is  stated  in  the 
table  as  required.  It  is  much  more  economical  to  use  9-horse 
power  from  a  12  or  15  horse,  than  from  a  nine  or  ten  horse  engine. 
The  machine  may  be  driven  by  any  power  less  than  that  given  in 
the  table,  yielding  a  product  per  hour  smaller  in  the  same  pro- 
portion. 

10x7 — (No.  2.)  Will  take  in  a  stone  10  inches  wide  and  7 
inches  thick,  and  is  quite  an  effective  machine.  It  may  be  set  to 
break  to  any  size  down  to  ^  inch,  and  can  be  used  for  the  same 
purposes  as  the  10x5,  but  receiving  pieces  two  inches  thicker  is 
preferred  in  many  cases.  It  will  do  a  good  deal  in  the  preparing 
of  road  metal.  It  is  one  of  the  most  salable  sizes. 

15x5  —  (No.  3).  This  machine  takes  in  a  stone  only  5  inches 
thick,  but  being  15  inches  wide  is  a  more  effective  machine  than 
the  10x5,  but  is  used  for  same  purposes  when  a  larger  product  is 
required. 

15x7  and  15x9  —  (Nos.  4  and  5).  These  are  the  sizes  most 
salable,  and  best  adapted  to  general  purposes.  They  are  the  sizes 
almost  uniformly  used  for  breaking  stone  for  Me  Adam  roads  and 
Ballasting  railroads  and  for  concrete.  They  are  also  used  exten- 
sively at  smelting  furnaces  —  also  at  copper  and  other  mines,  to 
take  the  product  of  the  coarse  breakers  and  reduce  it  to  proper  size 
for  feeding  under  the  stamps. 

When  broken  by  hand  and  for  country  roads,  the  stones  should 
be  broken  on  the  storage  places  already  mentioned,  which  are  to 
be  established  along  the  side  of  the  road  every  200  to  250  feet. 
The  laborer  is  not  to  pound  the  stones  on  a  heap  of  such,  but  to 
use  one  large  stone  as  a  sort  of  anvil  to  break  the  others  on.  He 
is  to  use  a  light  hammer,  except  for  pieces  containing  more  than 
four  or  five  cubic  feet,  and  may  use  a  ring  with  a  handle  attached 
to  hold  the  stone  he  desires  to  break. 

In  order  that  the  road  shall  get  an  even  surface,  the  macadam 
must  all  be  of  one  size,  and  the  proper  size  for  the  macadam  de- 
pends on  the  degree  of  hardness  of  the  rock.  If  too  small,  it  turns 
to  dust;  if  too  large,  the  top  will  not  pack  even.  The  size  is  regu- 


THE  SCIENCE  OF  ROAD  MAKING. 


lated  by  the  use  of  a  ring  as  a  gauge,—  every  stone  being  obliged 
to  be  capable  of  falling  through  this  ring  in  any  direction  it  may  be 
dropped.  Hard  stones  should  be  one  to  one  and  a  quarter,  softer 
ones  one  and  a  half,  and  the  softest  two  inches  in  diameter.  Larger 
sizes  give  less  perfect  roads.  In  loading  and  otherwise  handling 
macadam,  a  many  and  close-pronged  pitchfork  should  be  used 
instead  of  a  shovel,  so  as  not  to  mix  in  any  earth  or  sand,  and  so 
sift  out  the  stone  dust  and  chips. 

The  macadam  being  properly  prepared  and  loaded  up,  it  is 
spread  over  the  foundation  in  two  or  three  successive  layers. 
Each  layer  should  be  rolled,  but  the  top  and  last  one  must  be 
rolled  to  make  a  good  road.  Nor  will  rolling  alone  do  the  work. 
Two  other  helps  are  needed :  the  use  of  a  building  material,  to  act 
as  a  cement  between  the  broken  stone,  and  sprinkling.  It  is  diffi- 
cult to  prescribe  in  words  just  what  to  use  as  binding  material,  and 
just  how  much  to  sprinkle  and  roll;  common  sense  will  in  most 
cases  be  a  safe  enough  guide.  In  the  macadamized  streets  of  Paris 
the  rule  is  to  roll  till  a  single  piece  of  macadam  placed  under  the 
roller,  will  be  crushed,  without  being  pressed  into  the  road  surface. 
Gravel  somewhat  mixed  with  clay  by  nature,  but  not  too  much, 
is  probably  best  as  a  building  material.  Clean  coarse  sand  is  very 
good.  Other  substances  will  do,  where  it  would  cost  too  much  to 
procure  either  of  the  above. 

A  late  writer  in  the  "Journal  of  the  Society  of  Civil  Engineers 
and  Architects,"  at  Hannover,  calls  attention  to  the  practice  in  Bo- 
hemia of  making  foundation  roads  by  setting  first  the  foundation 
course,  spreading  a  thin  layer  of  the  binding  material  on  that,  and 
the  broken  stone  on  top  of  this  again.  The  subsequent  rolling  has 
the  effect  of  forcing  the  binding  material,  slowly  and  gradually, 
from  beneath  upwards  into  and  through  the  broken  stone.  The 
writer  states  that  he  himself  has  tried  a  system  of  road  construction 
that  consists  of  a  combination  of  the  two  methods  hitherto  used, 
with  good  results,  namely:  first,  a  foundation  course,  a  thin  layer 
of  binding  material  on  •this,  then  the  broken  stone,  another  thin 
layer  of  binding  material,  and  then  wet  down  and  roll. 

The  subject  of  rollers  is  one  demanding  some  attention.  In 
general,  people  are  apt  to  over-estimate  the  value  of  a  roller  with 
respect  to  its  weight.  It  will  be  evident  on  reflection  that  a  roller 
should  be  as  heavy  per  inch  in  length  of  roller,  as  a  loaded  wagon 
wheel  is  per  inch  of  tire;  or,  in  other  words,  if  we  have  a  wagon 


28  THE  SCIENCE  OF  ROAD  MAKING. 

with  tires  two  and  one-half  inches  wide  and  on  each  wheel  a  load 
of  say  one  ton,  the  roller  should  weigh  two-fifths  ton  for  every 
inch  in  length,  or  a  roller  three  feet  long  should  weigh  about  four- 
teen  and  one-half  tons>,  or  else  a  wagon  as  above  described  would 
exercise  more  pressure  on  the  road-bed  per  square  inch  than  the 
roller,  and  consequently  would  cut  into  the  rolled  surface  and  pro- 
duce ruts. 

The  proper  width  of  tire,  or  proper  load  upon  any  vehicle,  for 
a  given  width  of  tire,  is  a  question  that  occasionally  attracts  atten- 
tion. Bokelberg,  a  good  German  authority  on  the  subject,  in  an 
article  in  the  "Journal  of  the  Society  of  Civil  Engineers  and 
Architects,"  at  Hannover,  1858,  comes  to  the  conclusion  that  for 
four-wheeled  vehicles,  upon  a  broken  stone  road,  the  loads  should 
vary  with  the  widths  of  tires,  as  follows: 

WIDTH  OF  TIRES.      INCHES.  LOAD  IN  LBS. 

2  tO  3  5,000   to   6,600 

3  "  4  6,600    u  8,800 

4  "  5  11.000 

5  "  6  13000 

6  '•  7  15,000 

7  and  over.  16,500 

Further  conclusions  are:  that  the  best  width  of  tire,  measured 
when  they  are  new,  for  the  transportation  of  freight,  is  from  four 
to  seven  inches ;  this  width  being  best  for  the  easy  traction  of  the 
load  no  less  than  for  a  minimum  wear  of  the  road  surface.  To 
make  the  tires  wider  than  seven  inches  does  not  diminish  the  force 
required  to  move  the  load,  and  unnecessarily  increases  the  dead 
weight  of  the  wagons. 

Road-rollers  are  of  two  principal  kinds:  those  pulled  by  horses 
and  those  propelled  by  steam.  The  latter  are  for  many  reasons 
the  best.  In  the  first  place  they  can  be  made  as  heavy  as  desiredr 
without  proportionally  increasing  the  cost  of  propelling  them,  and 
being  self-propelling,  the  only  track  they  make  is  that  of  the  roller, 
whereas  with  horse  rollers,  the  hoof-marks  of  the  horses  are  a 
great  objection.  Then  again  in  the  amount  of  work  they  will  do 
at  a  certain  cost,  they  excel  horse  rollers.  They  may  be  briefly 
described  as  a  sort  of  locomotive  mounted  on  three  or  four  very 
broad  and  heavy  wheels,  these  latter  being  the  road  rollers. 

An  excellent  pamphlet  on  the  subject  of  steam  road-rollers  is 
the  "  Report  on  the  Economy  of  Maintenance  and  Horse-draught 
through  Steam  Road-rolling,"  by  Frederick  A.  Paget,  E.  &  N.  F. 
Spon.,  1870.  Readable  articles  on  the  same  subject  are:  "Steam 
Road-roller,"  Engineering,  Oct.  4,  1867.  "Paris  Kind  of  Steam 
Road-roller,"  Engineering,  May  7,  1869  "  Cost  of  Operating 


THE  SCIENCE  OF  ROAD  MAKING.  29 

Steam  Road-rollers,"  Engineering,  June  18,  1869.  "Good  Steam 
Road-roller,"  Engineering,  Jan.  14,  1870.  "Economy  of  Steam 
Road-rolling,  Engineer,  April  i,  1870.  "How  to  use  the  Road- 
roller  during  alternate  Thawing  and  Freezing,"  Annales  des  P. 
&  C.,  1877,  P'  I25'  ^n  ^e  sPrmg  and  fall  on  finished  roads,  and 
occasionally  during  the  first  construction  or  reconstruction  of  roads, 
the  surface  becomes  sticky  mud,  and  to  roll  the  road  at  those  times, 
or  to  travel  on  it,  tears  up  the  covering  and  spoils  the  whole.  If 
at  such  times  the  roller  be  constantly  sprinkled  and  kept  wet  while 
it  is  being  used,  it  will  shed  the  mud  or  road  covering,  instead  of 
tearing  it  up,  and  will  consolidate  the  road  in  a  very  superior  man- 
ner. And  this  method  requires  less  water  (only  about  one  gallon 
to  one  and  a  half  gallons  per  100  feet  of  travel)  than  the  method 
formerly  used  under  these  circumstances  of  converting  the  sticky 
mud  into  liquid  mud,  by  copiously  wetting  down  the  whole  road. 

There  are  several  varieties  in  use  in  France  and  England,  and 
two  at  least  of  the  English  kind  have  been  imported  into  this 
country,  one  for  the  New  York  Central  park,  the  other  for  the 
Arsenal  Grounds  in  Philadelphia.  The  cost  of  the  Central  Park 
steam  road-roller  made  by  Aveling  &  Porter,  of  Rochester,  Kent, 
England,  was  about  $5,000,  set  up  in  New  York,  and  the  amount 
of  work  it  will  do  in  one  day  at  a  running  expense  of  $10,  has 
been  given  as  equal  to  that  of  a  seven-ton,  eight-horse  road-roller 
in  two  days  at  $20  per  day,  or,  in  other  words,  it  will  do  the  same 
work  at  one  quarter  the  running  cost  and  in  one-half  the  time,  of 
a  first-class  horse  road-roller. 

Since  1870  many  other  steam  road-rollers  have  been  bought 
by  various  parties  in  the  United  States.  Thus  there  is  one  owned 
by  Daniel  Brennan,  a  road  contractor,  in  Orange,  N.  J. ;  the  city 
of  New  Haven,  Conn.,  has  run  one  with  great  success  for  several 
years ;  after  many  years  of  agitation  on  the  subject,  the  city  of  Bos- 
ton now  owns  and  operates  a  steam  road-roller ;  and  so  on. 

The  best  horse  road-roller  of  which  the  writer  has  any  cogni- 
zance is  the  one  shown  by  the  annexed  drawings  in  plan,  elevation, 
and  in  perspective. 

(The  town  of  Maiden,  Mass.,  has  built  a  horse  road-roller, 
according  to  the  plan  here  described.) 

It  originates  in  Chemnitz,  Germ-any,  but  can,  of  course  be  easily 
made  by  any  machine-shop  or  foundry.  The  hollow  roller  is 
made  of  cast-iron,  and  is  so  arranged  that  it  may  be  filled  with 
water  when  it  is  to  be  used  in  heavy  rolling ;  when  not  in  use  and 
.about  to  be  moved  from  place  to  place,  the  \otex  is  allowed  to  run 

/0p™§fc 

fiUHIVEBSITI 


THE    SCIENCE    OF   ROAD    MAKING. 


THE  SCIENCE  OF  ROAD  MAKING. 


31 


out,  thus  materially  lessening  the  load.  A  circular  cast-iron  frame 
A,  surrounds  the  roller,  and  carries  the  axle  bearings  of  the  same. 
The  outside  of  this  frame  is  turned  to  form  a  groove  in  which  a 
strong  wrought-iron  ring  is  fitted  in  such  a  manner  that  it  will 
turn  easily  around  the  former.  This  wrought-iron  ring  consists 
of  two  semi-circular  parts,  at  whose  junction  the  pole  is  attached 
on  one  side,  and  on  the  other  an  extension  bar,  carrying  the  bal- 
ance weight  Cj  which  may  be  shifted  by  means  of  the  set  clamp  d, 
or  turned  up  by  means  of  the  hinge  b.  Pins  going  through  the 
holes  at  £,  fasten  this  ring  or  allow  it  to  be  turned  for  the  purpose 
of  pulling  the  roller  in  the  contrary  direction,  when  required. 
The  brake  is  shown  aty,y,  and  consists  of  four  wooden  brake- 
blocks,  attached  by  iron  shoes  to  a  bar  behind  them  and  having 
rubber  packing  between  the  shoes.  The  screws  shown  and  the 
handles  ^,  are  used  to  operate  these  brakes.  The  cranks  /»,  work- 
ing the  screws  n,  operate  the  scrapers  /,  which  are  used  to  keep 
the  roller  clean  in  muddy  weather.  The  frame  A,  is  made  heavier 
at  0,  so  as  to  have  increased  weight  there  to  balance  the  whole 
frame- work  in  turning  around.  The  support  ^,  and  the  guide 
wheel  k,  might  be  dispensed  with.  A  great  saving  in  time  and  in 
movements  hurtful  to  the  road  is  effected  by  making  the  frame 
circular  as  described,  thus  allowing  the  roller  to  be  turned  with  the 
greatest  ease.  The  dimensions  are  figured  on  the  drawing.  A 
roller  of  this  kind  four  and  one-half  feet  in  diameter,  and  three 
and  one-half  feet  long,  and  weighing  some  four  tons  when  empty, 
would  cost  perhaps  $560  to  $600;  one  5  ft.  by  3  ft.  8  in.,  weighing 
about  five  and  one-quarter  tons  (empty,)  some  $700  to  $750. 
Leaving  off  the  break,  would  diminish  the  cost  about  $50. 

Before  leaving  the  subject  of  macadam  top  roads,  it  ought  to 
be  mentioned  that  a  bed  of  rubble  stone  10  or  12  in.  deep,  merely 
spread  uniformly  over  the  road-bed  as  a  foundation,  is  better  than 
nothing  at  all,  but  can  never  make  the  same  quality  of  road  as  the 
rough  paving  described  above. 

The  following  data  are  to  be  used  in  estimating  the  cost  of  the 
kind  of  road  just  described.  Rough  foundation  paving,  pieces 
5  to  6  in.  long,  filling  up  crevices  and  ramming  the  whole  with 
hand  rammers,  costs,  after  the  material  has  been  brought  to  the 


THE  SCIENCE   OF  ROAD  MAKING. 


L 


3 

F 

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1 

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1 

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THE  SCIENCE  OF  ROAD  MAKING. 


33 


spot,  one  day's  work  of  a  common  laborer  for  every  four  square 
yards,  this  assuming  that  the  paver  gets  one  and  two-thirds  com- 
mon laborer's  wages.  Same  kind  of  paving  if  set  in  sand  will 
cost  one  day's  work  of  a  common  laborer  for  every  two  and  one- 
quarter  square  yards. 

These  figures  for  the  cost  of  setting  rough  pavement  for  a 
foundation  course  have  been  objected  to  by  an  American  road  con- 
tractor, as  entirely  too  high,  he  claiming  to  set  20,  and  even  50 
square  yards  to  a  man  per  day.  An  explanation  of  these  different 
figures  probably  lies  in  the  phrase,  "  ramming  the  whole  with 
hand  rammers "  ;  in  the  general  quality  of  the  work  done,  etc. 
The  writer's  own  opinion  is,  that  no  very  fine  work  is  necessary  in 
the  construction  of  the  foundation  course.  Its  duties  are,  to  remain 
pervious,  and  not  to  settle  unevenly.  The  same  contractor  above 
mentioned  wrote,  in  1870:  "  I  put  down,  and  keep  in  perfect  order 
for  a  year  from  the  time  of  completion,  a  1 2-inch  road  (6  to  7  inch 
foundation,  5  to  6  inch  surfacing)  at  a  distance  from  the  quarry  of 
three  miles  (materials  exclusively  quarried  trap  rock),  for  $1.50 
per  square  yard;  wages  of  men  average  $2.25  per  day,  and  of 
transportation,  $1.25  per  cubic  yard.  This  includes  my  profit." 

To  make  macadam  by  hand  costs,  for  sizes  from  i  *^  to  i  ^  in. 
of  very  hard  rock,  one  day's  work  for  every  0.6  to  0.44  cubic 
yards,  for  less  hard  rock,  one  day's  wages  will  make  0.7  to  0.6 
cubic  yards,  and  of  soft  rocks  1.76  to  1.17  cubic  yards. 

In  1872  the  estimated  cost  of  crushing  stone  by  the  Blake 
machine  ranged  from  30  to  60  cents  per  cubic  yard ;  to  crush  the 
same  stone  by  hand,  it  was  estimated  would  cost  from  $1.20  to 
$3.00  per  cubic  yard. 

To  spread  14-12  cubic  yards  of  macadam  is  also  about  a  day's 
work. 

Gravel  Top. —  Instead  of  the  macadam  top  described  in  the  pre- 
ceding articles,  screened  gravel  may  be  used.  These  roads  are  the 
favorite  ones  in  Central  Park,  New  York,  and  are  probably  the 
best  road  there  is  for  pleasure  drives.  It  is  a  matter  of  some  doubt 
yet  whether  they  do  as  well  for  heavy  trucking  as  they  do  for 
light  vehicles.  The  foundation  for  these  gravel  roads  should  be 
the  same  as  the  rough  paving  for  the  macadam  road ;  some  pieces 
were  built  in  Central  Park  having  a  rubble  stone  foundation,  but 
they  are  not  recommended  by  their  builders.  The  gravel  to  be 
JJsed  for  the  top  must  be  selected  with  some  care ;  it  should  be  of  a 
hard  kind  of  stone,  clean,  that  is,  free  from  clay,  etc.,  of  the  right 


34 


THE  SCIENCE  OF  ROAD  MAKING. 


THE  SCIENCE  OF  ROAD  MAKING. 


35 


color,  etc.  It  is  put  on  in  two  layers,  each  rolled,  and  the  top  one 
made  compact  and  firm,  by  spreading  and  mixing  in  some  good 
binding  material,  sprinkling  and  rolling.  There  need  be  no  fear 
of  making  a  poor  road  by  using  the  smoothest,  most  water- worn 
pebbles,  free  from  all  sand,  etc.,  in  making  a  road-top.  The  upper 
portions  of  the  river  Rhine  are  remarkable  for  the  clean,  smooth 
pebbles  that  form  its  bed  to  a  very  great  depth.  These  pebbles 
are  dredged  up  and  used  in  road-building,  making  an  excellent 
road-covering  at  a  small  expense.  There  are  many  miles  of  such 
roads  in  Baden  and  in  the  Bavarian  Rhine  Provinces. 

In  gravelly  soil  all  the  materials  that  are  needed  for  a  good 
road  are  frequently  on  the  spot;  they  only  need  sorting  out  and 
re-laying.  For  this  reason  a  common  gravel  sieve  often  consti- 
tutes the  principal  instrument,  whose  judicious  use  will  make  a 
good  road  out  of  a  miserable  string  of  ruts  and  cobbly  elevations. 
It  would  be  only  necessary  to  sift  out  and  separate  the  soil  under 
the  road  to  a  sufficient  depth,  into  cobbles,  coarse  gravel,  fine 
gravel  and  sand ;  then  replace  them  in  the  order  named  and  with 
the  proper  thickness  of  layers  of  each;  wet  down  and  roll,  and  the 
result  would  be  a  good  road.  As  regards  the  advisability  of  well 
constructing  roads,  the  following,  from  the  Bath  (Maine)  Times, 
of  May  n,  1870,  is  not  without  instruction.  (The  Waltham  roads 
therein  spoken  of  are  also  mentioned  in  the  extracts  from  a  report, 
which  is  printed  in  the  Appendix) :  u  I  will  here  submit  a  com- 
parison of  the  cost  of  our  road,  with  those  of  the  town  of  Wal- 
tham, noted  for  its  good  roads.  Waltham  has  51  miles  of  roads; 
the  expense,  including  everything,  of  maintaining  their  highways, 
except  sidewalks,  for  seven  years  previous  to  1868,  was  $3,357  per 
year,  or  $66  per  mile.  In  1868,  with  60  miles  of  road,  including 
probably  the  building  of  9  miles,  the  cost  was  $6,000,  or  $100  per 
mile.  The  city  of  Bath  has  not  over  32  miles  of  roads.  The 
average  cost  of  repairs  on  our  roads  for  the  three  past  years  is 
$10,153;  not  including  the  expense  of  sidewalk,  $317  per  mile. 
At  this  rate,  if  we  reduce  the  cost  of  repairs  of  our  roads  to  $100 
per  mile,  we  could  afford  to  hire  money  at  7  per  cent,  and  expend 
$100,000  upon  their  permanent  improvement,  and  it  would  be 
vastly  cheaper  to  do  so  than  to  continue  our  present  system." 

Keeping  Roads  in  Repair. —  This  subject  properly  finds  its 
place  here,  being  a  matter  of  skill  and  a  thing  of  debate  only  in 
the  case  of  what  we  have  called  foundation  roads;  pavements  and 
trackway  roads,  to  be  considered  after  this,  need  no  special  direc- 
tions as  regards  their  repair  or  maintenance. 

After  a  road  has  been  properly  rolled,  and  the  surface  made 


THE  SCIENCE  OF  ROAD  MAKING. 


THE  SCIENCE  OF  ROAD  MAKING. 


37 


compact  and  smooth,  it  should  always  be  maintained  in  that  con- 
dition, no  matter  how  great  is  the  amount  of  travel  on  it.  UA 
stitch  in  time  saves  nine,"  here  as  well  as  elsewhere.  The  ten- 
dency is  to  produce  ruts;  these  gather  water;  this  soaks  up  the 
road-bed  and  spoils  the  whole.  The  problem  can  be  put  in  this 
way:  To  have  a  good  road  it  is  necessary  that  there  be  no  dust  or 
mud  on  the  same,  and  that  there  be  no  ruts;  therefore,  remove  the 
dust  and  mud  as  fast  as  they  are  formed,  and  fill  up  the  ruts  as  fast 
as  they  are  made.  The  whole  matter  is  here  in  a  nut-shell.  It 
may  be  thought,  at  the  first  view,  that  this  is  too  expensive  a  sys- 
tem. Its  principal  beauty  lies,  however,  in  the  fact  that  it  costs 
less  per  mile  of  road  kept  one  year  than  the  pernicious  system  of 
annual  or  semi-annual  repairs,  as  will  be  shown  and  proved.  The 
above  two  rules  —  sweep  off  the  mud  and  dust  as  fast  as  they  are 
formed,  and  fill  up  the  ruts  and  bad  places  with  new  material  as 
fast  as  they  appear  —  are  all  that  is  necessary  to  be  carried  out  in 
order  that  there  be  continually  a  good  road.  Without  continual 
repairs,  there  can  be  no  such  thing  as  a  constantly  good  road  — 
a  proposition  that  cannot  too  often  be  repeated.  By  repairing  a 
road  annually,  or  twice  a  year,  it  matters  not  which,  the  result  is, 
strictly  speaking,  a  good  road  at  NO  time  during  the  whole  year. 
The  road  is  wretched  just  alter  repairs;  it  becomes  passable  after  a 
while,  and  deteriorates  from  that  day  forward,  until  it  is  again  made 
wretched;  and  so  on,  ad  finitum,  according  to  the  present,  only 
too  commonly  followed  system.  By  the  other  method  is  offered 
us  a  road  as  smooth  as  a  floor,  year  in,  year  out,  and,  let  it  not  be 
forgotten,  at  a  less  expense. 

A  French  engineer,  named  Tresaguet,  was  the  first,  in  1875,  to 
call  attention  to  this  proper  method  of  making  road  repairs.  His 
system  —  the  above  described  one — was  adopted  in  Baden  in  the 
year  1845,  and  has  been  long  in  universal  use  in  all  the  active 
European  countries.  The  two  tables  below  give,  the  first,  the 
actual  average  quantity  of  road  macadam  used  per  mile  of  road  in 
Baden  to  make  the  repairs  in  one  year,  and  show  the  decrease  after 
1845.  The  second  gives,  in  the  first  column,  the  cost  of  materials 
and  labor  required  to  repair  one  league  for  one  year  according  to 
the  old  way,  —  this  column  being  calculated  for  the  years  following 


THE  SCIENCE  OF  ROAD  MAKING. 


1845  from  the  cost  of  the  preceding  years,  and  allowing  for  the 
increased  value  of  labor  and  materials,  —  while  in  the  second  col- 
umn we  have  the  actual  cost,  as  it  was  with  the  system  followed 
at  the  time : 

TABLE  I. 


YEAR. 

Cubic  yards  used  per 
mile  in  one  year  to  re- 
pair roads. 

1832  
1839.       •                                  

218.6 

198.7 
127    2 

18*6 

V1  '4 
8fi    A 

i860  

°V*4 

93-4 

TABLE  II. 

COST  OF  REPAIRS  OF  ONE  LEAGUE  OF  ROAD. 


YEAR. 

By  old  way  of  so  doing, 
in  florins. 

By  system  of  continual 
repairs,  in  florins. 

1835,           .           .          •           • 
I840,         '  .           .          v          .          . 

1,002 

1,086 
1,170 

1,002 
1,086 

Q7c3  6 

1,254. 

975^t 
06=;  *  0 

i»339 

9    5^0 

835  5 

1860,         .         .         .         , 

1,423 

J31TO 
97854 

v/   TTO 

These  figures  are  taken  as  given  by  the  chief  engineer  of  the 
Baden  Public  Works,  Mr.  Keller.  He  quaintly  adds:  "These 
tables  give  clear  evidence  in  favor  of  the  reduced  cost  by  the 
adopted  system.  That  roads  are  better  now  than  they  formerly 
were,  everybody  knows."  Another  German  engineer  expresses 
himself  to  the  same  effect  in  a  little  different  way.  "  It  costs  no 
more,"  says,  he,  "to  keep  the  roads  in  repairs  now  (1864),  than  it 
did  twenty  years  ago,  when  this  method  (of  continual  repairs)  was 
not  in  use,  although  labor  is  now  three  times  and  materials  are 
twice  as  dear  as  they  then  were."  There  seems  to  be  no  doubt  of 
the  superiority  of  the  continual  repair  system  in  every  respect, 
producing  very  much  better  roadsj  and  at  the  same  time  costing 
less.  It  need  only  be  tried  with  us  to  be  thenceforth  adopted. 


THE  SCIENCE  OF  ROAD  MAKING. 


39 


How  TO  REPAIR  ROADS  ON  THE  CONTINUOUS  SYSTEM. 

We  suppose  the  material  for  the  road  covering  to  lie  in  regular 
measured  heaps,  all  ready  to  be  used,  at  the  storage  places,  once  or 
twice  above  mentioned,  as  being  200  to  250  feet  apart  alongside  of 
the  road,  but  not  encroaching  upon  it.  Then  for  every  two  or 
three  miles  of  road,  a  so-called  road-keeper  is  employed  to  do  the 
necessary  work  and  repairs.  An  enumeration  of  his  duties  will 
comprise  at  the  same  time  an  essay  on  the  art  of  road  repairing. 

1.  The  road-keeper  is  to  remove  the  dust  formed  in  dry  weather 
by  sweeping  with  a  brush  broom.     This  is  done  to  greatest  ad- 
vantage just  after  a  slight  shower.     In  muddy  weather  it  is  essen- 
tial that  the  mud  be  removed  by  means  of  brooms  or  hoes.     A 
little  mud  on  the  surface  causes  ruts,  and  much  mud  softens  up  the 
whole  road  surface.     The  mud  is  to  be  raked  up  in  heaps  alongside 
of  the  road,  there  left  to  dry  and  then  carted  off.     To  hinder  as 
much  as  possible  the  formation  of  any  mud,  the  surface  drainage 
must   remain   unimpaired;   should  it  be  out  of  order,  the  water 
'standing  on  the  road  is  to  be  swept  off.     To  diminish  the  wear  of 
the  road  in  dry  times,  the  road  should  be  sprinkled.* 

2.  Inasmuch  as  the  covering  gradually  wears  off,  notwithstand- 
ing all  precautions,  it  must  be  renewed,  and  should  be  so  renewed 
gradually,  in  the  same  measure  as  it  wears  off.     The  best  time  to 
'put  on  new  road  metalling  is  during  continuous  wet  weather. 

i  3.  In  filling  up  holes,  the  bottom  of  the  same  is  to  be  swept 
jdean  of  mud,  then  filled  up  level  with  the  remainder  of  the  road, 
|not  in  a  heap  so  high  above  it  as  to  obstruct  travel. 

Every  care  should  be  taken  to  have  the  new  material  join  as 
speedily  as  possible  with  the  old  portion  of  the  road,  and  it  should 
be  so  well  laid  that  it  will  give  the  least  possible  hindrance  to 
vehicles,  which  will  then  not  avoid  the  patched  places. 

4.  When  many  ruts  occur  in  a  short  distance,  the  deepest  only 
are  to  be  filled  at  first.  After  the  patching  in  these  has  become 
solid,  then  the  rest  are  to  be  attended  to.  Long  ruts  or  wheel 


*  Bowles,  in  his  book,  "  Our  New  West,"  mentions  the  case  of  the  stage  road 
from  Sacramento  to  Virginia  City,  via  Placerville,  one  hundred  and  fifty  miles 
long,  and  having  an  annual  traffic  of  seven  or  eight  thousand  heavy  teams,  and 
whose  proprietors  found  that  the  simplest  and  cheapest  way  of  keeping  it  in  repair 
during  dry  weather  was  to  sprinkle  the  whole  of  it,  —  one  hundred  and  fifty  miles 
of  mountain  road. 


40  THE  SCIENCE  OF  ROAD  MAKING. 

tracks  are  not  to  be  filled  up  the  whole  length  at  once,  but  only 
short  pieces  at  a  time.  If  this  precaution  is  neglected,  vehicles 
avoid  such  places,  and  new  ruts  are  formed  elsewhere. 

5.  Inasmuch  as  more  material  is  worn  off  in  a  dry  season  than 
can  be  put  on,  there  are  then,  when  wet  weather  comes,  large 
places  to  be  repaired.  These  must  be  mended  by  degrees,  never 
filling  up  a  piece  larger  than  8-10x4-7  ^ee^  a*  a  ^me5  and  not 
having  these  pieces  too  near  together;  when  these  have  become 
solid,  then  some  more  may  be  fitted  in  and  so  on  till  the  whole 
is  done 

Should  it  however  become  absolutely  necessary  to  repair  a 
piece  of  road  in  dry  weather,  the  place  where  the  new  macadam 
is  to  be  deposited  must  be  loosened  up  with  a  pick,  then  the  new 
material  put  on  and  a  solid  top  formed  by  the  judicious  use  of  stone 
dust  or  other  binding  material  and  sprinkling  with  water  and 
pounding  down  with  the  shovel,  or  by  what  may  be  called  "  pud- 
dling" until  the  whole  be  solid.  Should  a  frost  or  very  dry 
weather  occur  immediately  after  macadam  has  been  put  on  the 
road  in  wet  weather  so  that  the  same  will  not  join  on  the  rest  of 
the  road  surface,  the  whole  must  be  removed,  cleaned  and  returned 
to  the  storage  heaps  for  future  use.  A  layer  of  macadam  over  the 
whole  road  should  never  be  put  on  without  treating  it  immediately 
afterwards  in  the  manner  described  above  for  building  new  roads,, 
that  is,  mixing  in  binding  material  with  the  top  course  and  rolling 
it  in  wet  weather,  or  after  sprinkling. 

The  road-keeper  is  naturally  also  the  person  to  see  to  the 
proper  delivery  on  the  part  of  the  contractors,  if  such  there  be,  of 
the  road  material  in  the  prescribed  places,  and  to  attend  to  the 
measuring  of  the  same. 

In  short  and  to  sum  up,  it  is  his  business  to  keep  the  road  in 
good  order,  and  with  proper  men  and  surveillance  the  desired 
result  is  achieved  easily  and  at  a  less  cost,  than  by  any  other  sys- 
tem. The  quantity  of  macadam  required  to  keep  a  certain  length 
of  road  in  repair  varies  very  much;  it  depends,  as  we  have  seen,, 
on  the  care  with  which  the  repairs  are  made,  naturally  also  on  the 
kind  of  stone  used  and  on  the  amount  of  travel  over  road.  For  a 
width  of  road  =  twenty  feet,  the  average  quantities  required  per 


THE  SCIENCE  OF  ROAD  MAKING.  41 

year  to  keep  a  length  of  ten  feet  in  repair,  on  the  system  of  con- 
tinuous repairs,  has  been  given  as  follows: 

Cubic  ft.      Cubic  yds. 

1.  Good  material  and  heavy  travel 15-20  =  . 55-. 74 

2.  Good  material  and  medium  amount  of  travel 10-15  =  .  37-.  55 

3.  Good  material  and  light  travel •. 5-10  =  .18-.  37 

4.  Medium  material  and  heavy  travel. 20-25  =  .74-. 92 

5.  Medium  material  and  medium  amount  of  travel 15-20  =  .5 5-.  74 

6.  Medium  material  and  light  travel 10-15  =  .37-. 55 

7.  Third  rate  material  and  heavy  travel 25-30  =  .92-1 .01 

8.  Third  rate  material  and  medium  amount  of  travel 20-25  =  .74-.  92 

9.  Third  rate  material  and  light  travel 15-20  =  .  55-.  74 

These  are  the  quantities  as  given  by  one  authority,  but  from  a 
comparison  with  the  amounts  actually  used  during  a  period  of  ten 
years  on  thirty-nine  roads,  having  very  various  amounts  of  travel 
upon  them  and  being  repaired  with  all  kinds  of  road  metal,  it 
would  seem  that  the  foregoing  figures  are  very  ample. 

The  exact  relation  between  the  quantity  of  road  material  that 
is  necessary  to  keep  a  road  in  repairs,  and  the  amount  of  travel  over 
it,  is  still  a  matter  of  intelligent  observation  and  discussion.  The 
quantity  required  does  not  seem  to  be  proportional  solely  to  the 
amount  of  travel,  even  with  one  and  the  same  kind  of  stone  used 
on  the  same  road;  as  will  appear  also,  when  it  is  considered  that 
were  there  no  travel  over  the  road  at  all,  the  surfacing  would,  nev- 
theless,  wear  out  by  the  action  of  the  frost,  the  rain,  etc.  As- 
recent  an  article  as  the  "  Annales  des  P.  and  C,"  1877,  p.  226,  is  de- 
voted to  this  subject,  and  does  not  arrive  at  any  definite  general  con- 
clusion. 

REPAIRS  OF  MACADAMIZED  AND  MUCH  FREQUENTED  STREETS 

IN  CITIES. 

In  this  case,  where  the  amount  of  travel  in  one  day  is  often 
greater  than  that  of  a  month  or  more  on  the  town  road,  the  system 
of  continuous  repairs  ceases  to  be  the  best  available,  on  accowit  of 
the  incessant  throng  of  vehicles  not  giving  any  repaired  place  a 
chance  to  become  solid  before  it  is  again  ploughed  up  and  scattered. 
Thus  in  the  city  of  Paris  on  the  Boulevards,  etc.,  the  continuous 
system  has  been  abandoned  and  the  practice  now  is  to  let  the  street 
gradually  wear  down  three  to  four  inches,  then  close  half  of  it 
(divided  "  fore  and  aft ")  to  travel,  loosen  it  all  up  with  picks  and 
put  on  a  layer  three  or  four  inches  (best  not  to  put  on  more  than 
that),  spread  a  thin  layer  of  sand  over  this,  sprinkle  and  roll  heavily.. 


42  THE  SCIENCE  OF  ROAD  MAKING. 

It  often  happens  that  the  men  put  too  much  of  the  sand  on;  in  that 
case,  the  road,  after  it  is  all  done,  is  finally  well  watered  and  the 
roller  again  passed  over  it  a  number  of  times.  This  operation 
causes  the  superfluous  binding  material  to  come  to  the  surface  in 
the  shape  of  thin  mud  and  leaves  the  road  covering  as  hard  and 
smooth  as  mosaic,  making  a  most  excellent  driveway.  It  emits  a 
sonorous,  ringing  sound  on  being  driven  over  and  remains  clean 
and  without  mud  throughout  the  heaviest  rain-storms.  The  rolling 
of  the  streets  in  Paris,  is  done  by  a  company  owning  a  large  num- 
ber of  steam  rollers;  in  paying  them  for  work  done,  the  city  was 
obliged  to  go  back  to  first  principles  for  a  measure  of  such  work,  it 
being  found  impossible  to  estimate  correctly  by  the  square  measure 
of  surface  rolled  to  such  and  such  a  degree  of  hardness.  The  meas- 
ure adopted  is  that  of  weight  multiplied  into  the  distance  it  has  been 
moved,  or  "  feet  pounds  "  as  we  should  say.  It  has  been  found 
from  many  years  experience  that  to  roll  one  cubic  meter  of  maca- 
dam requires  4-5  "  Kilometer-tonnes,"  and  this  is  true  whether  the 
layer  of  macadam  be  three  and  one-quarter  or  ten  inches  thick. 
Expressed  in  our  measures  this  is  11,020-13,775  feet  tons  @  2,000 
ft>s.  =  2.09-2.61  mile  tons  per  cubic  yard  of  macadam. 

The  advocates  of  the  steam  road-roller  claim,  that  by  means  of 
that  machine,  they  are  enabled  to  make  a  road  that  will  wear  out 
evenly  and  uniformly  for  4  or  5  inches,  so  that  the  operation  of 
patching  need  never  be  resorted  to.  The  steam  road-roller  can 
also  be  used  for  "  picking  "  up  a  road,  for  which  purpose  the  roller 
is  armed  with  sharp  spikes,  and  is  then  driven  over  the  surface  to 
be  "  picked  "  up. 

PAVEMENTS  AND  TRACKWAYS. 

No  essay  on  roads  would  be  complete  without  some  mention  of 
these  two  species  of  road  surface,  though  the  use  of  the  former  is 
confined  principally  to  streets,  and  that  of  the  latter  is  out  of  date. 

Pavements  are  either  of  stone,  wood,  iron,  various  concretes,  as- 
phalt, and  may  be  of  still  other  substances. 

Stone  Pavements. — The  modern  sizes  of  paving  stones  may  be 
seen  from  the  following  cases.  The  Boston  size  is  <tf4 ' '  X  3*4 ' ' 
X7"  deep;  New  York  Belgian,  6-8' '  X 5-6' '  X6-fj"  deep;  new 
Broadway  pavement,  also  called  Guidet  pavement,  3^-4^ ' '  X  10- 
I4/ '  X7^-8^ ' '  deep.  This  last  is  laid  with  the  long  sides  of  the 


THE  SCIENCE  OF  ROAD  MAKING. 


43 


stones  across  the  street;  and,  as  far  as  the  author's  judgment  goes, 
is  the  best  size  for  stone  pavement  there  is.  The  Boston  size  is  too 
small,  and  allows  of  no  bond  between  the  separate  paving  stones. 
Further,  the  weakest  part  of  each  stone  being  its  edge,  it  follows 
that  the  more  edges  there  are  in  a  given  surface  of  pavement,  the 
speedier  will  it  wear  out,  each  stone  becoming  rounded  and  slippery. 
It  is  only  the  excellent  workmanship  and  great  care  displayed  in 
setting  these  stones  in  Boston  that  prevents  these  facts  from  being 
at  once  apparent  to  all.  When  it  is  added  that  in  setting  pave- 
ments, the  natural  soil,  except  it  be  sand  or  fine  gravel,  is  in  all 
cases  to  be  excavated  12-19  inches,  and  then  filled  up  5-12  inches, 
according  to  the  solidity  of  the  subsoil,  with  clean,  coarse  sand  or 
fine,  clean  gravel,  and  the  paving  stone  set  in  this  and  well  ram- 
med down  with  hand  rammers,  about  as  much  is  said  on  this  topic 
as  can  be  said  without  going  into  long  details. 

From  four  and  one-half  to  six  cubic  feet  of  sand  are  required 
for  every  square  yard  of  paving.  In  setting  two  different  pave- 
ments, the  same  written  rules  may  be  exactly  followed  in  either 
case,  yet  one  be  much  better  than  the  other,  so  much  depends  here 
upon  good,  careful,  conscientious  workmanship. 

Wooden  Pavements. — There  are  so  many  kinds  of  these,  that  it 
would  be  out  of  place  to  enumerate  and  describe  them  here.  Their 
advantages  are,  less  wear  on  tires  and  horses,  less  noise  and  smooth 
traction ;  a  disadvantage,  is  their  slipperiness  in  the  winter.  There 
seems  to  be  a  sort  of  notion  that  wood  pavements  and  coal  tar  must 
go  hand  in  hand;  but  there  certainly  is  no  necessity  for  this.  Coal 
tar  is  applied  as  a  preservative  to  the  wood ;  but  it  must  be  acknowl- 
edged that  many  better  ones  are  known  and  indeed  are  used,  to  the 
utter  exclusion  of  coal  tar,  in  all  cases  where  it  is  desired  to  pre- 
serve wood,  except  in  this  of  wood  pavements.  No  wood  should 
be  used  in  paving  that  has  not  been  first  subjected  to  some  approv- 
ed method  of  preservation,  or  impregnation,  as  it  is  frequently 
called.  The  best  manner  of  setting  the  same  is  still  a  mooted  point, 
which  it  would  be  presumptuous  at  present  to  decide. 

A  valuable  contribution  to  the  subject  of  wooden  pavements,  is 
the  report  of  the  Commission  appointed  by  the  city  of  Boston  to 
consider  this  subject,  in  1872,  City  document,  No.  100,  1873.  The 
Commission  come  to  the  conclusion,  that  the  best  way  to  preserve 


44  THE  SCIENCE  OF  ROAD  MAKING. 

the  wood  that  is  put  down,  is  by  the  method  called  Burnettizing, 
after  its  inventor,  Sir  H.  Burnett,  of  England,  in  1838.  It  consists 
of  treating  the  wood  to  be  preserved  with  chloride  of  zinc.  The 
Commissioners  wisely  add:  "  Your  Commisioners  are  of  the  opin- 
ion that  if  the  city  adopts  any  method  of  preserving  blocks  to  be 
used  for  pavements,  some  additional  security  should  be  had  that  the 
treatment  of  the  wood  shall  be  thorough  and  complete."  As  re- 
gards the  construction  of  the  pavement,  the  Commissioners  recom- 
mend spruce  blocks  (for  this  section  of  the  country),  lay  stress  on 
the  necessity  of  a  solid,  uniformly  constituted,  and  rolled  gravel 
foundation,  and  then  say:  "The  rows  or  blocks  should  be  set 
square  across  the  street,  and  should  be  about  4  inches  thick  at  top, 
with  spaces  of  about  one-half  inch  between  the  rows.  This  may 
be  done  with  blocks  of  uniform  thickness  set  apart,  or  with  taper- 
ing blocks  half  an  inch  thicker  at  bottom  than  at  top.  The  latter 
arrangement  is  the  more  costly,  but  it  is  believed  by  some  that  it 
will  stand  better,  by  reason  of  its  covering  the  whole  surface  of  the 
foundation.  Longer  trial  is  necessary  to  settle  this  point  beyond 
dispute.  Blocks  of  only  a  short  chamfer  at  the  top  leave  the  inter- 
space too  narrow,  as  the  blocks  wear  down."  The  Commission 
named  consisted  of  "two  chemists,  two  practical  mechanics,  and 
one  civil  engineer." 

Cast-iron  pavements  are  out  of  favor  on  account  of  their  great 
cost,  and  concrete  pavements  are  a  matter  of  experiment  as  yet. 

Asphalt  pavements  are  chiefly  used  in  Paris.  They  are  slip- 
pery in  wet  weather,  and  produce  a  very  disagreeable,  penetrating 
dust  in  dry  weather.  It  is  necessary  to  prepare  a  bed  of  macadam 
to  lay  them  on,  and  they  are  not  used  in  Paris  except  in  streets 
where  the  gas  pipes  are  carried  either  in  the  sewers  or  under  the 
sidewalks,  as  any  leak  of  gas  would  destroy  them.  Their  use  is  a 
matter  of  doubtful  economy. 

Trackways  are,  as  has  been  mentioned,  out  of  date.  Where  a 
common  road  does  not  suffice  now-a-days,  a  railroad  is  built;  but 
time  was  when  trackways  were  of  considerable  importance.  They 
consist,  if  of  stone,  of  large  flat  stones,  say  12 ' '  deep  and  4-6  feet 
long  by  !4"-i6"  wide,  solidly  bedded  in  two  parallel  rows,  at 
such  distance  apart  as  to  make  of  each  row  a  track  for  the  wheels. 
The  space  between  is  paved.  They  are  of  course  very  expensive, 
but  cost  little  to  repair,  and  enable  a  horse  to  pull  a  very  great 
load.  As  has  been  mentioned,  Telford  made  use  of  such  a  track- 
way, to  avoid  cutting  down  a  hill,  on  his  Holyhead  road.  There 
were  two  hills,  each  a  mile  in  length,  with  an  inclination  of  5  in  a 


THE  SCIENCE  OF  ROAD  MAKING.  45 

hundred.  It  would  have  cost  $100,000  to  reduce  this  grade  to 
41^  in  a  hundred,  but  nearly  the  same  advantage,  in  diminishing 
the  tractive  force  required,  was  obtained  by  keeping  the  5  in  a  hun- 
dred grade,  with  moderate  cuttings  and  embankments,  and  making 
stone  trackways,  at  a  total  expense  of  less  than  half  the  former 
amount. 

"  Plank  roads,"  once  so  much  in  vogue  in  the  United  States, 
may  not  improperly  be  classed  among  roads  with  trackways,  and, 
with  them,  also  among  the  things  that  were.  From  their  perish- 
able nature,  they  can  never  advantageously  do  more  than  help  the 
development  of  a  new  country,  and  in  this,  as  well  as  other  States, 
are  yearly  becoming  more  and  more  impracticable  on  account  of 
the  constantly  increasing  price  of  lumber. 

ON  THE  RESISTANCE  TO  MOTION  OR  THE  FORCE  REQUIRED  TO 
MOVE  VEHICLES  ON  DIFFERENT  KINDS  OF  ROADS. 

Before,  as  well  as  since  the  introduction  of  railways,  engineers 
in  England,  Germany  and  France  made  many  experiments  on  the 
force  necessary  to  pull  different  vehicles,  at  various  speeds  over 
^various  surfaces.  To  enumerate  the  details  of  all  these  experi- 
ments would  be  perhaps  useless;  a  few  general  results  only  are 
here  given. 

Experiments,  as  above  indicated,  were  made  by  Edgeworth, 
Count  Rumford,  Bevan,  Macneill,  Minard,  Navier,  Perdonnet, 
Poncelet,  Flachat,  Morin,  Kossak,  Umpfenbach,  Gerstner,  and 
no  doubt  others,  a  list  of  authorities  that  proves  the  subject  to  have 
been  well  nigh  exhausted.  The  experiments  of  Morin,  made  in 
1838-41,  appear  to  have  been  made  with  a  degree  of  care  and 
accuracy,  leaving  nothing  more  to  be  desired,  and  the  following 
table  is  an  extract  from  his  results,*  and  gives  that  fraction  of  the 
weight  of  the  vehicle  and  load,  which  is  required  to  move  them  on 
a  level  road : — 

*  A  full  account  of  Morin's  experiments  on  the  resistance  to  motion  of  vehi- 
cles, on  the  wear  caused  by  different  vehicles  on  roads  and  on  the  loads  different 
vehicles  shou'd  carry  so  as  to  produce  the  same  wear,  may  be  found  in  Morin, 
Experience  sur  le  tirage  des  Voitures,  Paris,  1842. 


46 


THE  SCIENCE  OF  ROAD  MAKING. 


CHARACTER  OF  THE  VEHICLE.. 

r£ 

i   c 

.  § 

CHARACTER  OF  THE  ROAD. 

Jj  ^ 

*^ 

?   "ft 

S-g'w 

>  rt 
!>  u 

A 

ll* 

£•3% 

|l* 

y 

*M 

Firm  soil,  covered  with  gravel  4'  7-6//  deep,  . 

A 

t 

i 

1 

Firm  embankment  covered  with  gravel  iX"- 

i^"  deep,     ...... 

TV 

TV 

TV 

TV 

Earth  embankment  in  very  good  condition,  . 

A 

A 

A 

A 

Bridge  flooring  of  thick  oak  plank, 

TV 

TV 

& 

A 

BROKEN  STONE  ROAD. 

walk 

trot 

walk 

trot 

In   very   good  condition,  very  dry,  compact 
and  even,       ...... 

TV 

A 

A 

^ 

& 

TV 

A  little  moist  or  a  little  dusty,    .         . 

TO 

A 

A 

TT 

A 

A 

Firm,  but  with  ruts  and  mud,     . 

A 

A 

& 

A 

A 

TV 

Very  bad,  ruts  4"-4^''  deep,  thick  mud,     . 

TV 

TV 

TV 

TV 

TV 

TV 

Good  pavement,  -1              ,"    . 
(  Covered  witn  mud,  . 

A 
A 

ft 

S 

A 

A 

s 

t 

To  take  an  example,  suppose  we  have  a  truck  weighing  with 
its  load  9,000  Ibs.  How  many  pounds  traction  will  be  required  to 
move  the  same? 

Ans. — On  firm  soil,  gravel  4"  —6"  deep,  that  is,  a  newly  re- 
paired road,  as  we  often  find  it,  (J  by  table),  1000  Ibs.;  on  best 
kind  of  embankment,  (^V  by  table,)  310.3  Ibs.;  on  broken  stone 
road  in  good  condition,  (-£%  by  table,)  166.6  Ibs.;  on  broken  stone 
road,  deep  ruts  and  mud,  (J^-  by  table,)  643.  Ibs. ;  on  a  good  pave- 
ment, (^  by  table,)  138.5  Ibs.  Or,  since  the  tractive  force  of  a 
medium  horse  when  working  all  day  is  said  to  be  about  125  Ibs., 
we  need  in  the  first  case,  8  horses;  in  the  second  case,  2^  horses; 
in  the  third  case,  about  ij^  horses;  in  the  fourth  case,  about  5 
horses;  and  in  the  fifth  case,  only  one  good  horse  to  move  the 
same  entire  load  all  day. 

These  facts  expressed  in  the  preceding  page  or  two  in  striking, 
yet  perhaps  dry  figures,  can  be  nearly  as  well  given  in  popular 
language. 

Says  a  correspondent  (Dr.  Holland),  of  the  Springfield  Repub- 


THE  SCIENCE  OF  ROAD  MAKING. 


47 


lican,  writing  from   England,  after  describing  the  kind  of  horses 
in  use  there:— 

"  Now  with  all  these  horses  the  rule  follows  that  every  pound 
of  muscle  does  just  as  much  work  on  the  road  as  two  pounds  do 
in  America.  The  cab  and  omnibus  horse  does  twice  as  much  as 
the  same  horse  does  in  America.  The  draft  horse  does  as  much  at 
the  dray  as  two  ordinary  dray  horses  in  America,  and  the  little 
horses,  which  are  driven  mainly  in  butchers'  carts  and  grocers* 
carts,  will  tire  a  cab  horse  to  follow  them  with  no  load  at  all. 

"  In  connection  with  these  statements  it  should  be  recorded  that 
the  speed  of  all  vehicles  in  the  streets  of  London,  whether  the  locali- 
ties be  crowded  or  not,  is  at  least  a  third  faster  than  it  is  in  corre- 
sponding streets  in  American  cities.  The  ordinary  speed  of  vehi- 
cles in  London,  in  which  passengers  or  light  loads  are  transported, 
is  one  which  is  considered  not  entirely  safe  in  Main  street,  Spring- 
field, Mass.,  and  one  which,  in  some  streets  of  Boston  or  New 
York,  would  be  at  once  checked  by  the  police.  A  man  who  sits 
in  a  'hansom'  finds  himself  driven  at  an  unprecedented  pace 
through  crowded  thoroughfares,  and  Yankee  though  he  may  be, 
he  will  often  wonder  whether  he  is  going  to  bring  up  at  last  with- 
out a  broken  neck. 

"  I  mention  this  matter  of  speed,  particularly,  because  it  shows 
that  even  more  work  is  done  by  one  horse  in  London,  than  by  two 
in  New  York.  He  not  only  draws  as  large  a  load,  but  he  travels 
with  greater  rapidity.  The  streets  of  London  present  such  a  spec- 
tacle of  headlong  activity  as  no  American  city  can  show,  in  conse- 
quence of  the  rapid  passage  of  all  sorts  of  vehicles  through  the 
streets.  I  might  add  to  this  statement,  touching  the  superior  speed 
of  the  London  horses,  a  word  about  the  greater  weight  of  the 
carriages  which  they  are  obliged  to  draw  behind  them.  All  car- 
riages are  built  more  heavily  in  Great  Britain  than  in  America. 
They  are  built  to  last,  and  many  of  them  seem  to  me  to  be  super- 
fluously heavy. 

"  The  point  which  I  wish  to  impress  upon  my  American  reader 
is  simply  this: — that  the  English  horse,  employed  in  the  streets  of  a 
city,  or  on  the  roads  of  the  country,  does  twice  as  much  work  as 
the  American  horse  similarly  employed  in  America.  This  is  the 


48  THE  SCIENCE  OF  ROAD  MAKING. 

patent,  undeniable  fact.  No  man  can  fail  to  see  it  who  has  his  eyes 
about  him.  How  does  he  do  it?  Why  does  he  do  it?  These  are 
most  important  questions  to  an  American.  Is  the  English  horse 
better  than  the  American?  Not  at  all.  Is  he  overworked?  I 
have  seen  no  evidence  that  he  is.  I  have  seen  but  one  lame  horse 
in  London.  The  simple  explanation  is  that  the  Englishman  has 
invested  in  perfect  and  permanent  roads  what  the  American  ex- 
pends in  perishable  horses  that  require  to  be  fed.  We  are  using 
to-day,  in  the  little  town  of  Springfield,  just  twice  as  many  horses 
as  would  be  necessary  to  do  its  business  if  the  roads  all  over  the 
town  were  as  good  as  Main  street  is  from  Ferry  to  Central.  We 
are  supporting  hundreds  of  horses  to  drag  loads  through  holes  that 
ought  to  be  filled,  over  sand  that  should  be  hardened,  through  mud 
that  ought  not  to  be  permitted  to  exist.  We  have  the  misery  of 
bad  roads,  and  are  actually  or  practically  called  upon  to  pay  a  pre- 
mium for  them.  It  would  be  demonstrably  cheaper  to  have  good 
roads  than  poor  ones.  It  is  so  here.  A  road  well  built  is  easily 
kept  in  repair.  A  mile  of  good  macadamized  road  is  more  easily 
supported  than  a  poor  horse." 

Other  results  of  Morin's  experiments  are  as  follows : 

1.  The  force  required  to  draw  a  vehicle,  is  directly  proportional 
to  the  load,  and  inversely  so  to  the  diameter  of  the  wheels ;  in  other 
more  common  words,  the  tractive  force  increases  in  the  same  ratio 
that  the  load  increases,  and  the  diameters  of  the  wheels  decrease. 

2.  On  a  paved  or  well  built  macadam   road,  the  tractive  force 
is  independent  of  the  width  of  the  tires,  provided  the  same  is  more 
than  three  or  four  inches.     On  compressible  roads,  such  as  new 
gravel,  on  a  meadow,  etc.,  the  tractive  force  diminishes  with  an 
increase  in  the  width  of  the  tires. 

3.  Other  circumstances  being   equal,  the  tractive  force  is   the 
same  for  vehicles  with  and  without  springs  as  long  as  the  horses 
are  not  moving  faster  than  a  walk. 

4.  On  paved  and  well  macadamized  roads  the  tractive   force 
increases  with  the  velocity,  according  to  the  law,  that  beyond  a 
velocity  of  2^  miles  per  hour  (3.3  feet  per  second)  the  increase  of 
the  tractive  force  is  in  direct  proportion  to  the  increase  in  velocity ; 


• 
THE  SCIENCE  OF  ROAD  MAKING. 


49 


this  increment  is  however  less,  the  softer  the  track  or  road  and 
According  as  the  vehicle  is  best  provided  with  springs. 

5.  On  soft  earth  embankments,  or  on  sand  or  sods,  or  on  streets 
newly  covered  with  gravel,  the  tractive  force  is  independent  of  the 
velocity. 

6.  On  a  well-made  pavement  of  regular  shaped  stone,  the  trac- 
tive force,  horses  on  a  walk,  is  about  three-fourths  of  that  on  a 
good  macadam  road,  but  with  horses  ©n  a  trot,  the  two  are  about 
equal. 

7.  The  wear  on  the  road  is  greater  the  smaller  the  diameter  of 
the  wheels  and  greater  in  the  case  of  vehicles  without,  than  for 
those  with  springs.     Most  road-rollers,  as   now  in  use,  have  two 
small  a  diameter  besides  being  two  light  and  consequently  do  not 
properly  compress  the  road  surface. 

8  The  tractive  force,  as  well  as  the  wear  on  the  road,  is  greater 
in  the  case  of  vehicles  that  have  their  wheels  placed  at  an  angle 
with  the  vertical  by  reason  of  the  ends  of  the  axle-trees  being  bent 
down,  than  for  those  that  have  their  wheels  set  plumb  and  the  cen- 
tre line  of  the  axle-trees  level. 


50  THE  SCIENCE  OF  ROAD  MAKING. 


PAET  II- 

ON   THE    "BEST    METHODS     OF    SUPERINTENDING    THE    CON- 
STRUCTION   AND    REPAIR   OF   PUBLIC  ROADS  IN  THIS  COM- 
MONWEALTH  "  (MASSACHUSETTS). 

In  looking  for  a  solution  of  this  question  the  people  of  the 
Commonwealth  man  turn  as  they  choose,  either  to  the  West  or  to 
the  East,  to  see  a  guiding  star;  to  the  city  of  Chicago,  or  to  the 
city  of  London,  both  under  a  republican  form  of  government,  alike 
or  similar  to  that  we  live  under.  It  lies  in  the  establishment  of  a 
Board  of  Works,  composed  of  a  number  of  able  men,  well  paid  for 
their  services,  gradually  changing  in  their  membership  in  the 
Board  who  shall  have  this  and  only  this  as  their  occupation,  and 
who  can  therefore  be  held  responsible  for  their  acts.  This  is  the 
system  that  has  been  adopted  both  in  London  and  in  Chicago  and 
with  remarkable  success  and  resultant  benefits.  There  are  many 
other  systems  in  use  in  foreign  countries  all  of  which  however 
seem  to  be  inapplicable  here,  placed  as  we  are,  under  so  different 
forms  of  government;  hence,  though  well  acquainted  with  the  sys- 
tems adopted  in  France  and  in  Germany,  the  writer  has  not  de- 
scribed them  here. 

The  history  of  "the  Metropolitan  Board  of  Public  Works  of 
the  City  of  London  "  is  about  as  follows : 

What  is  known  as  the  city  of  London  consists  in  reality  of  a 
great  number  of  what  we  should  call  towns,  there  called  parishes, 
and  of  which  the  "  City  of  London  "  is  only  one  single  member. 
Each  one  of  these  parishes  had,  and  still  has  in  most  respects,  its 
own  local  government,  and  in  consequence  took  care  of  its  drain- 
age, its  streets,  etc.,  etc.,  as  seemed  best  and  as  it  liked,  some  bet- 
ter, some  worse,  and  some  not  at  all.  This  state  of  things  in  the 
matter  of  drains  and  sewers  finally  led  to  a  most  deplorable  condi- 
tion of  affairs ;  there  was  not  nor  could  there  under  these  conditions 
be  such  a  thing  as  a  system  of  sewers,  and  consequently  a  proper 
and  adequate  drainage;  the  death-rate  increased  to  an  alarming  ex- 
tent and  matters  came  to  be  universally  regarded  as  past  all  endur- 


• 
THE  SCIENCE  OF  ROAD  MAKING. 


ance.  What  could  be  the  remedy?  No  well  grounded  complaint 
could  be  made  against  the  majority  of  the  men  composing  the  vari- 
ous local  governments,  since  they  were  good  and  honest  citizens, 
and  hence  no  change  in  the  separate  goverements  could  ever  bring 
relief.  The  fault  lay  not  in  the  men,  but  in  the  system  of  ruling 
they  were  called  upon  to  fulfill,  that  is,  in  the  incompetent  and 
faulty  treadmill  of  government  they  were  annually  called  upon  to 
keep  in  its  usual  operation.  It  was  then  seen  that  by  having  an 
elected  power  to  supervise  and  regulate  the  sewage  affairs  of  the 
whole  metropolis,  a  complete  system  of  drainage  could  be  carried 
out,  and  thus  only.  Such  a  regulating  power  is  exercised  by  the 
metropolitan  Board  of  Public  Works,  chartered  by  Act  of  Parlia- 
ment and  composed  of  members  elected  from  all  parts  of  London. 
It  is  perhaps  in  place  here  to  explain  what  is  meant  by  a  system  of 
sewers  as  the  same  definition  will  hold  good  in  other  matters;  as 
for  a  system  of  roads,  of  drainage  and  irrigation  of  lands,  etc. 
Perhaps  the  best  illustration  would  be  to  refer  one  to  the  veins  and 
arteries  in'  the  human  body,  or  to  the  body  of  a  tree,  from  its  trunk 
through  the  branches  growing  smaller  and  smaller  down  to  the 
smallest  twig  that  may  be  on  it.  It  will  be  at  once  seen  how  dif- 
ferent any  arrangement,  in  which  may  be  the  wisdom  to  contrive, 
the  strength  to  uphold  and  the  beauty  to  adorn,  like  this,  is  from  a 
miserable  patchwork  such  as  cannot  but  arise  where  the  separate 
parts  of  one  whole  are  each  left  to  guide  themselves  without  any 
unity  of  action  or  design,  as  to  their  final  resultant.  The  London 
Board  of  Public  Works  had  some  extraordinary  powers  conferred 
upon  it,  such  as  the  right  to  levy  assessments  on  real  estate  bene- 
fitted  by  their  improvements,  and  others.  Originally  constituted 
merely  to  plan  and  execute  a  system  of  sewerage  for  the  metropo- 
lis, this  Board  of  Public  Works  soon  showed  itself  so  useful  and 
beneficial  in  its  actions  that  other  matters  were  placed  in  its  charge, 
such  as  the  laying  out  of  new  streets,  the  building  of  the  Thames 
embankment, —  a  work  of  exceeding  great  magnitude  and  import- 
ance,—  and  there  seems  to  be  no  doubt  that  in  all  public  works 
London  will  find  it  advantageous  to  employ  its  Metropolitan  Board 
of  Public  Works. 

In  the  city  of  Chicago  there  has  been  a  Board  of  Public  Works 


52  THE  SCIENCE  OF  ROAD  MAKING. 

almost  from  the  very  start.  It  arose  there  from  the  union  of  the 
water  supply  and  the  sewerage  commissioners,  and  has  existed 
since  May,  1861.  No  less  than  in  London,  it  has  proved  to  be  of 
great  benefit  to  the  community ;  and  it  would  have  been  impossible, 
under  any  other  system,  to  have  executed  in  so  satisfactory  a  man- 
ner  the  many  and  useful  public  works  for  which  Chicago  is  famed. 
At  the  risk  of  introducing  in  this  place  some  very  dry  reading,  a 
general  synopsis  of  those  parts  of  the  city  charter  which  relate  to 
the  Chicago  Board  of  Public  Works  is  here  given.  The  whole 
may  be  found  in  a  copy  of"  Laws  and  Ordinances,  Chicago,  1866:" 

SEC.  i.  Establishes  a  body  known  as  the  "  Chicago  Board  of 
Public  Works,"  to  consist  of  (3)  three  members,  chosen  by  the 
people,  one  from  each  division  of  the  city. 

The  first  three  chosen  for  one,  two  and  three  years;  after  that, 
one  each  year  for  three  years. 

SEC.  2.  Each  member  of  board  shall  receive  annual  salary  of 
three  thousand  dollars  (by  Act  of  February,  1866);  give  bonds  for 
faithful  discharge  of  duties;  pay  over  all  moneys,  papers,  etc.,  at 
expiration  of  his  term,  or  when  ordered  by  city  council. 

SEC.  3.  Board  to  elect  president  and  treasurer,  and  make  by- 
laws. 

SEC.  4.  Majority  constitutes  quorum ;  records  to  be  kept  of  pro- 
ceedings; copies  of  all  plans,  estimates,  etc.,  to  be  kept;  report 
(annual)  to  be  rendered  on  or  before  each  year, 

or  when  required  by  city  council.  Each  member  authorized  to 
administer  legal  oaths. 

SEC.  5.  Board  shall  have  special  charge  and  superintendence, 
subject  to  the  laws  and  ordinances  of  the  city  council,  of  all  streets, 
lanes,  alleys,  etc.,  in  the  city  of  Chicago,  and  of  all  walks  and 
crossings  in  the  same,  and  of  all  bridges,  docks,  wharves,  public 
places,  landings,  grounds  and  parks  in  said  city,  and  of  all  halls, 
engine-houses,  and  other  public  buildings  in  the  city  belonging 
to  city,  except  school-houses,  and  of  the  erection  of  all  public 
buildings;  of  lamps  and  lights  in  streets,  etc.,  and  in  public  build- 
ings, and  repairs  of  same ;  of  the  harbor  works  and  improvements ; 
of  the  city  sewers  and  drains  and  of  the  water  works ;  of  the  fire- 
alarm  telegraph,  and  all  public  works  and  improvements  hereafter 


THE  SCIENCE  OF  ROAD  MAKING. 


53 


to  be  commenced  by  the  city,  as  well  as  such  other  duties  as  may 
be  prescribed  by  the  city  council  by  ordinance. 

SEC.  6.  All  applications  or  propositions  for  improvements  or  new 
works  of  kind  specified  in  section  five,  shall  hereafter  be  first  made 
to  Board  of  Public  Works,  or  if  made  first  to  city  council,  shall  be 
by  them  referred  to  Board.  Upon  receiving  application,  Board 
shall  investigate  the  same,  and  if  they  find  such  work  necessary 
and  proper,  shall  thus  report  to  city  council,  with  an  estimate  of 
the  expense  thereof.  If  they  do  not  approve  of  such  application, 
they  shall  report  the  reasons  for  their  disapproval,  and  the  city 
council  may  then  in  either  case,  reject  said  application  or  order  the 
doing  of  work  or  making  of  public  improvement,  after  having 
first  obtained  plans  and  estimates  thereof.  The  Board  may  also  in 
like  manner  recommend  whenever  they  think  proper,  any  improve- 
ment of  the  nature  above  specified,  though  no  application  has  been 
made  therefor. 

SEC.  7.  Shall  be  duty  of  Board  to  procure  for  city  full  plans 
and  estimates  of  contemplated  improvements,  when  so  ordered  by 
council. 

SEC.  8.  Whenever  any  public  improvement  shall  be  ordered  by 
city  council,  and  money  appropriated,  Board  shall  advertise  for  pro- 
posals for  doing  work;  plans  and  specifications  of  same  first 
placed  on  file  in  office  of  Board,  which  plans  and  specifications 
shall  be  open  to  public  inspection;  advertisement  to  state  work  to 
be  done,  and  to  be  published  ten  days  at  least.  The  bids  shall  be 
sealed  bids,  directed  to  bourd,  and  accompanied  by  bond  to  city, 
signed  by  bidder  and  two  responsible  sureties,  in  sum  of  two  hun- 
dred dollars,  conditioned  he  shall  do  work  if  awarded  to  him;  in 
case  of  his  default  to  do  so,  etc.  Bids  to  be  opened  at  time  and 
place  mentioned  in  advertisement. 

SEC.  9.  All  contracts  shall  be  awarded  to  lowest  reliable  bidder, 
and  who  sufficiently  guarantees  to  do  work  under  superintendence 
and  to  satisfaction  of  Board:  provided,  that  the  contract  price 
does  not  exceed  the  estimate,  or  such  other  sum  as  shall  be  satisfac- 
tory to  Board.  Copies  of  contracts  to  be  filed  with  city  comp- 
troller. 

SEC.  10.  Board  reserves  right,  in  contracts,  to  decide  questions 


54 


THE  SCIENCE  OF  ROAD  MAKING. 


as  to  proper  performance  of  work  and  meaning  of  contracts;  in 
case  of  improper  construction  may  suspend  work  and  relet  same, 
or  order  entire  reconstruction;  or  may  relet  to  other  contractors 
and  settle  for  work  done,  etc. 

In  cases  where  contractor  properly  does  work,  Board  may,  in 
their  discretion,  as  work  progresses,  grant  to  said  contractor  esti- 
mate of  amount  already  earned,  reserving  fifteen  per  cent,  there- 
from, which  shall  entitle  holder  to  receive  amount,  all  other  con- 
ditions being  satisfied. 

SEC.  n.  In  case  prosecution  of  any  public  work  be  suspended, 
or  bid  be  deemed  excessive,  or  bidders  be  not  responsible,  Board 
may,  with  written  approval  of  treasurer,  where  urgency  of  case 
and  interests  of  city  require  it,  employ  workmen  to  perform  or 
complete  any  improvement  ordered  by  council :  provided,  that  the 
cost  and  expense  shall  in  no  case  exceed  the  amount  appropriated 
for  the  same. 

SEC.  12.  All  supplies  of  materials  etc.,  when  costing  over  five 
hundred  dollars,  to  be  purchased  by  contract,  subject  to  same  con- 
ditions as  letting  out  work. 

SEC.  13.  Whenever  Board  think  necessary  for  interests  of  city, 
to  protect  same  from  damage  or  loss,  shall  report  thus  to  aldermen, 
and  reasons  for  same,  asking  power  to  give  contracts  without 
notice  required  above,  and  aldermen  may  grant  request:  provided, 
three-fourths  vote  for  it. 

SEC.  14.  Whenever  Board  is  of  opinion  work  may  be  better 
done  without  contract,  shall  so  report  to  council,  and  same  may 
authorize  Board  to  procure  machinery,  materials,  etc.,  hire  work- 
men, etc. :  provided,  a  three-fourths  vote  be  in  favor  of  granting 
authority. 

SEC.  15.  All  contracts  and  bonds  by  Board  to  be  in  name  of 
city. 

SEC.  16.  No  member  to  be  interested  in  any  contract;  all  con- 
tracts made  with  any  member  interested,  city  may  declare  void; 
any  member  so  interested  shall  forfeit  his  office  and  be  removed 
therefrom;  the  duty  of  every  member  of  Board  and  of  every 
officer  of  city  to  report  delinquency,  if  discovered. 

SEC.  17.  All  existing  contracts  executed  by  city,  by  water  or 
sewerage  department,  etc.,  to  be  carried  out  by  Board. 


THE  SCIENCE  OF  ROAD  MAKING. 


SEC.  1  8.  Board  shall  nominate  each  year  the  various  officers, 
now  provided  for  by  ordinance,  which  serve  in  the  departments 
under  their  special  charge,  the  city  engineer,  superintendent  sew- 
ers, streets,  etc.  Shall  be  empowered  to  employ  from  time  to  time 
such  other  superintendents,  clerks,  etc.,  as  they  may  deem  neces- 
sary, subject  to  ordinance  as  regards  pay,  etc. 

SEC.  19.  Board  to  have  charge  and  superintendence  of  works 
made  lor  city,  and  paid  for  by  private  individuals  or  by  State. 
Plans  for  same  to  be  approved  by  Board. 

SEC.  20.  Board  shall,  on  or  before  every  year, 

submit  to  auditor,  by  him  to  be  presented  to  council  with  annual 
estimate,  statement  of  the  repairs  and  improvements  necessary  to 
be  undertaken  for  current  year,  and  of  the  sums  required  by  Board 
therefor;  report  to  be  in  detail;  report,  having  been  revised  by 
council,  sums  required  shall  be  provided  for  in  annual  tax  levy. 
All  moneys  to  be  paid  to  any  person  out  of  moneys  so  raised,  shall 
be  certified  by  president  of  Board  to  auditor,  who  shall  draw  war- 
rant on  treasurer  therefor,  stating  to  whom  payable  and  to  what 
fund  chargeable  ;  such  warrant  to  be  countersigned  by  president  of 
Board. 

SEC.  21.  Board  to  keep  accounts  showing  moneys  received 
and  spent,  clearly  and  distinctly,  and  for  what  purpose.  Accounts 
to  be  always  open  for  inspection  of  auditor  or  any  committee  ap- 
pointed by  city  council. 

The  object  of  introducing  this  synopsis  here  has  been  to  give 
a  complete  picture  of  just  what  such  a  Board  of  Public  Works  is. 
It  will  be  seen  upon  a  little  examination  how  entirely  different  a 
thing  it  is  from  the  usual  and  only  too  customary  "committee." 
Perhaps  the  greatest  fault  of  a  committee  is  its  entire  lack  of  what 
might  be  called  body  and  soul.  If  corporations,  as  has  been  said, 
have  no  souls,  a  committee  may  be  said  to  have  neither  body  nor 
soul.  It  is  alive  to-day,  wields  great  power,  decides  vital  and  im- 
portant questions,  and  yet  is  nowhere  to-morrow,  and  seemingly 
even  its  component  atoms  have  vanished  from  the  face  of  the 
earth.  It  is  amusing  and  yet  sad,  when  the  action  of  some  such 
committee  has  caused  trouble  to  read  some  time  after,  that  it  all 
•"  is  exceedingly  discreditable  to  whoever  is  responsible  for  it." 


56  THE  SCIENCE  OF  ROAD  MAKING. 

How  much  better  to  have  a  conservative,  expert  and  reliable  body, 
the  members  of  which  have  no  other  business  than  to  attend  to 
their  duties  as  such,  who  are  well  paid  for  it  and  consequently  can 
at  any  time  be  held  strictly  responsible  for  their  actions.  With 
such  a  power,  wisely  governing  and  regulating  the  roads  of  this 
Commonwealth,  it  would  be  an  easy  matter  to  make  thorough  im- 
provements in  the  legislation  concerning  roads  and  in  the  roads 
themselves. 

These  are  two  changes  the  need  of  which  is  generally  felt  at 
present  and  has  found  expression  in  various  ways. 

It  may  be  well  to  quote  one  at  least,  notable  for  saying  very 
much  in  little  compass,— of  these  calls  for  improvement,  in  this 
connection,  and  adding  some  more  as  belonging  to  this  subject  in 
the  form  of  an  interesting  appendix.  Says  Gov.  Claflin  in  his  In- 
augural: "Few  things  are  of  greater  importance  to  a  community, 
or  a  surer  test  of  civilization,  than  good  roads.  Those  of  our  citi- 
zens who  have  visited  Europe  are  unanimous  in  the  opinion  that 
our  public  roads  are  far  inferior  to  those  of  other  countries,  where 
the  means  of  easy  and  safe  communication  are  better  appreciated. 
The  science  of  road-making  is  apparently  not  well  understood ;  or,, 
if  it  is,  the  present  modes  of  superintending  the  construction  and 
repair  of  roads  are  so  defective  that  the  public  suffers  to  an  extent 
of  which  few  of  us  are  aware.  It  may  be  found  upon  investigating 
the  cause  of  our  miserably  poor  and  ill-constructed  roads,  that  the 
laws  relating  to  this  subject  need  revision,  so  as  to  give  more  uni- 
formity in  their  construction  and  the  repair  of  our  highways.  It 
is  evident,  also,  that  the  science  of  road-making  should  have  a 
prominent  place  in  the  course  of  applied  mathematics  at  the  Massa- 
chusetts Agricultural  College." 

We  stand  then  in  this  matter  of  roads  at  precisely  the  same 
point  that  the  good  people  of  London  did  ten  or  a  dozen  years 
ago  in  the  matter  of  their  drainage,  and  our  remedy  is  the  same. 
The  fault  lies  in  the  machinery  of  government;  originally  built 
up  to  cater  to  the  wants  and  needs  of  a  newly  settled  country, — 
a  colony  breaking  a  path  through  the  wilderness, —  it  has  long 
since  ceased  to  satisfy  the  demands  of  the  present  State  in  no  mat- 
ter so  essentially  as  in  that  of  its  government  and  laws  relating  to- 


THE  SCIENCE  OF  ROAD  MAKING. 


common  roads  and  highways.  This  is  a  subject  requiring  special 
knowledge,  to  be  acquired  only  by  long  experience  or  the  shorter 
rrethod  of  imbibing  the  experience  of  others,  which,  on  analyzing 
it,  is  all  that  any  study  amounts  to;  formerly  it  was  not  so,  and 
most  any  one  sufficed  to  make  improvements  on  Indian  paths* 
We  need  then  an  expert  government  on  this  point. 

There  should  be  a  distinction  made  between  first,  second  and 
third  class,  or  between,  as  they  might  be  called,  State,  County  and 
Town  roads;  the  first  two  should  not  be  left  to  be  dealt  with  as  it 
is  the  pleasure  of  each  town.  A  chain  cannot  be  perfect  unless 
every  link  in  it  is  so;  no  more  can  a  road.  The  State  must  attend 
to  the  State  and  County  roads  and  set  a  proper  example  at  least  ta 
be  followed  by  the  towns  in  the  case  of  their  roads.  We  need  then 
a  higher  power  than  that  of  the  towns. 

It  has  been  previously  shown  how  we  need  a  power  that  can 
be  held  responsible  and  is  somewhat  permanent,  and  to  put  it  all 
together,  we  need,  to  order  and  maintain  our  highways,  a  Massa- 
chusetts Board  of  Public  Works.  For  some  years  it  would  have 
its  hands  full  in  improving  the  existing  main  roads  and  laying  out 
some  new  ones,  but  in  course  of  time,  as  in  the  older  countries  of 
Europe,  its  principal  business  would  be  the  maintenance  of  the 
roads.  It  must  be  remembered  that  the  Board  of  Public  Works 
is  merely  the  intelligent  servant  and  adviser  of  the  legislative  and 
executive ;  whatever  sums  the  legislature  appropriates  for  certain 
objects,  that  is  taken  by  the  Board  and  made  to  yield  its  most  in 
the  shape  of  work  accomplished.  Beyond  this  and  keeping  its- 
accounts,  it  has  nothing  to  do  with  money  or  taxation. 

The  small  state  of  Baden,  a  part  of  Germany,  has  been  hereto- 
fore mentioned  as  a  model  in  road  construction  and  the  care  of  the 
same.  From  a  brief  history  of  the  roads  of  that  country  and  their 
present  management,  we  may  take  some  useful  notes.  The  account 
is  that  of  the  Chief  Engineer  of  the  department  of  "  Roads  and 
Hydraulic  Engineering,"  which  has  this  matter  in  charge  and  is 
therefore  reliable. 

"  In  Baden  the  condition  of  the  roads  has  been  a  subject  of 
great  care.  Within  the  last  forty-five  years  many  millions  have 
been  spent  upon  them,  and  experience  has  shown  this  expenditure- 


58  THE  SCIENCE  OF  ROAD  MAKING. 

to  be  one  of  those  most  advantageously  spent.  As  most  of  the 
roads  are  well  laid  out,  and  as  there  are  plenty  of  them,  there 
remains  now  (1863)  mainly  the  keeping  in  repair  of  the  roads  to 
be  attended  to  and  not  to  build  any  new  ones.  Our  endeavor  now 
is,  to  do  this  at  the  minimum  of  cost.  Statistics  gathered  on  this 
subject,  show  good  results  and  point  out  to  us  the  means  of  arriv- 
ing at  still  better  ones.  The  present  road  law  was  made  in  1810. 
That  part  of  the  old  law  which  relates  to  the  maintenance  of  roads 
is  still  in  force,  but  that  part  requiring  labor  as  a  road-tax  was 
abolished  in  1831,  and  likewise  most  of  the  road  police  regulations. 
The  appropriation  for  roads  had  to  be  increased  250,000  florins  to 
pay  for  the  abolished  road-tax  labor  and  to  make  up  170,000  florins 
previously  received  from  tolls,  which  were  also  abolished  in  1831. 
The  system  now  is  as  follows :  All  town  roads  are  taken  care  of  by 
the  towns.  The  State  merely  appoints  and  pays  a  road-master,  so 
called,  who  superintends  fifteen  or  twenty  road-keepers  and  reports 
on  the  state  of  the  roads,  the  reasons  for  their  bad  condition,  if  that 
be  the  case,  what  is  needed,  etc.  The  law  for  second  class  or 
county  roads  was  formerly,  that  when  they  were  of  importance  to 
several  towns,  they  had  all  to  help  maintain  the  same.  As  this 
gave  rise  to  continual  bickering  and  quarreling,  in  which  the  road 
suffered  most,  it  was  changed  in  1856.  They  are  now  taken  care 
of  under  the  direction  of  the  State  and  paid  for  partly  by  the  State 
and  partly  by  the  towns  in  which  they  are  situated.  Most  of  the 
roads  under  this  head  are  those  which  have  risen  in  importance 
since  the  building  of  railroads,  and  are  generally  those  that  lie  per- 
pendicular to  the  direction  of  the  railroad  they  are  influenced  by. 
The  towns  not  having  the  means  very  often  to  properly  improve 
and  repair  such,  it  was  found  necessary  and  expedient  to  give  them 
the  aid  of  the  State,  and  in  order  to  procure  the  necessary  funds, 
all  roads  that  run  parallel  to  railroads  and  all  those  that  had  lost 
their  importance  by  the  construction  of  railroads,  were  in  1855 
stricken  from  the  list  of  state  roads.  These  latter  as  the  name  im- 
plies, are  wholly  under  the  care  and  kept  up  at  the  expense  of  the 
State. 

In  1835,  the  total  length  of  the  State  roads  wa»  .  .  1,430.8  English  mile* 
In  1855,  "  "  a  "  1,500.8  «•  ' 


THE  SCIENCE  OF  ROAD  MAKING. 


In  1855,  by  excluding  several  State  roads,  this  last  length  English  Miles. 

was  reduced  to  ......     1,142.4 

In  1861,  it  had  increased  to     ......  1,190.0 

Second  class  Roads  (keeping  partly  paid  for  by  State.} 
In  1835,  the  length  of  these  was          .....        467.6  English  miles. 

In  1861,         "  "  ......     630.0  " 

So  that  the  State  had,  in  1861,  in  all,  1,820  English  miles  of 
road  to  maintain,  the  towns  helping  to  pay  on  six  hundred  and 
thirty  miles  thereof. 

The  areas,  population,  and  population  per  square  mile  of  Baden, 
Prussia,  France,  Hanover  and  Massachusetts,  according  to  recent 
census,  are  as  follows  : 

Country.  Year.  Area,  sq.  miles.  Population.    Pop.  per  sq.  mile. 

Baden.  1871,                        5,^91.  1,461.562.  248. 

Prussia.  1871.                     134,045.  24,643,698.  184. 

France.  1872.                   204,088.  36,102,921.  177. 

Hanover.  1871.                      14,857.  1,963,080.  132. 

Massachusetts.  1875.                        7,800.  1,651,912.  212. 

Baden  did  have,  at  a  time  when  her  population  per  square  mile 
was  less  than  it  is  now,  and  Prussia,  France,  Hanover,  and  many 
other  countries  that  could  be  named,  have  now  got,  and  for  the  past 
40  or  50  years  have  had,  a  system  of  common  road  management 
and  resultant  common  roads,  of  the  character  above  described; 
while  Massachusetts  with  a  population  of  212.  per  square  mile,  and 
corresponding  wealth,  and  others  of  the  States  of  the  Union,  have 
a  species  of  highway  management,  and  its  resultant  and  corres- 
ponding sort  of  highways,  which,  in  thinking  of  the  roads  of  the 
countries  named,  are  but  as  evidences  of  a  partial  civilization. 

"  The  statistics  of  the  road  repairs  are  kept  in  the  following 
manner.  The  road-keepers  are  required  to  keep  a  record  of  all 
draught  animals  that  pass  in  either  direction.  Horses  that  are 
being  ridden,  animals  not  before  a  vehicle,  and  teams  going  to  and 
from  the  fields,  are  not  counted.  These  records  are  kept  only  dur- 
ing the  working  hours.  Likewise,  not  during  the  whole  year,  but 
only  four  months  in  each  year,  so  selected  as  to  give  an  average 
amount  of  travel.  The  travel  on  the  road  on  Sundays  and  out  of 
working  hours  is  taken  from  a  few  observations;  it  is  a  very  small 
percentage  of  the  whole.  At  the  end  of  the  year  these  records 
and  observations  are  collected  and  graphically  represented  on  a 
map  of  the  whole  State.  The  different  roads  are  drawn  of  a  dif- 
ferent thickness  of  line,  according  as  the  amount  of  travel  on  them 
is  greater  or  less.  The  quantity  of  road  metal  used  per  yard  of 


60  THE  SCIENCE  OF  ROAD  MAKING. 

road,  and  the  kind  of  metal  used,  give  the  data  for  another  such 
map,  in  which  the  different  colors  of  the  roads  represent  the  differ- 
ent materials  used  in  their  repair,  and  the  figures  on  them  and  their 
thickness  show  the  number  of  cubic  yards  per  mile  required  to 
keep  the  road  in  order.  Finally,  we  have  a  third  map,  which  indi- 
cates, by  the  thickness  of  the  several  lines  representing  the  roads 
and  by  the  figures  on  them,  the  total  cost  per  mile  of  repairing  the 
road  one  year." 

With  this  picture  of  a  country  happy  and  prosperous,  in  the 
possession  of  good  and  well-kept  roads,  it  may  be  well  to  leave  the 
subject. 

Massachusetts  wants  for  her  proper  development,  much  better 
roads  than  she  now  has;  and,  reckoning  for  a  period  of  say  fifty 
years,  she  can  have  these  good  roads,  and  have  them  kept  in  order, 
at  a  less  cost  than  that  of  keeping  up  the  present  poor  ones  for  the 
same  time.  Besides  this,  we  should  see  in  the  one  ease  a  healthy 
state  of  internal  convnunications  and  trade;  in  the  other  an  absence 
of  both.  Let  each  citizen  so  act  and  do  his  part,  that  these  benefits 
may  accrue  to  the  Commonwealth. 


THE  SCIENCE  OF  ROAD  MAKING.  6 1 


APPENDIX. 


For  the  sake  of  arriving  at  some  practical  end,  I  have  requested 
the  gentlemen  to  whom  the  prizes  for  essays  were  awarded  to  sug- 
gest what  form  of  legislation  would  be  desirable  as  a  change  from 
our  present  inefficient  system  of  road  management,  to  one  which 
should  promise  better,  more  economical  and  more  satisfactory  re- 
sults. The  large  and  varied  experience  and  observation  of  these 
gentlemen,  all  of  whom  are  competent  engineers,  entitle  their 
opinions  and  judgment  to  favorable  consideration  ;  and  the  follow- 
ing, submitted  by  them,  may  serve  as  a  basis  or  outline  for  future 
legislation.  C.  L.  F. 

AN    ACT  FOR  THE  MORE  PERFECT  CONSTRUCTION  AND  MAIN- 
TENANCE OF  THE  COMMON  ROADS  OR  HIGHWAYS  THROUGH- 
OUT THIS  COMMONWEALTH  (MASSACHUSETTS). 
SEC.  i.  Establishes  a  body  to  be  known  as  the  State  Board  of 
Highways  and  Bridges,  to  consist  of  three  skillful  civil  engineers, 
or  persons  practically  expert  in  the  science  of  road-making,  to  be 
.appointed  by  the   Governor  with  the  advice  and  consent  of  the 
Council,  and  to  have  their  office  in  the  State  House. 

SEC.  2.  It  shall  be  the  duty  of  the  Attorney- General,  person- 
ally or  by  his  deputy,  to  give  his  council  and  opinion  on  such  mat- 
ters as  he  may  be  called  upon  by  the  Board,  for  which  service  his 
•compensation  shall  be 

SEC.  3.  The  first  appointment  of  members  of  the  Board  of 
Highways  and  Bridges  shall  be  made  on  or  before  , 

and  there  shall  be  appointed  one  member  each  for  the  terms  of 
one,  two,  and  three  years;  after  that  there  shall  on  or  before 
each  year  be  appointed  one  member  for  the  term  of  three  years. 

SEC.  4.  Each  member  of  the  Board  shall  receive  an  annual 
salary  of  dollars;  give  bonds  for  the  faithful  discharge 

of  his  duties;  pay  over  all  moneys,  papers,  etc.,  at  the  expiration  of 
his  term  or  when  ordered  by  the  Governor  and  Council. 

SEC.  5.  Board  are  to  elect  a  president  and  treasurer,  and  make 
their  own  by-laws. 

SEC.  6.  A  majority  of  the  Board  constitutes  a  quorum ;  records 
to  be  kept  of  all  the  proceedings ;  copies  of  all  plans,  estimates,  etc., 


62  THE  SCIENCE  OF  ROAD  MAKING. 

to  be  kept;  report  to  be  rendered  on  or  before  each 

year,  or  when  required  by  the  Governor  and  Council.     Each  mem- 
ber authorized  to  administer  legal  oaths. 

SEC.  7.  Said  Board  shall  prepare  and  submit  to  the 
legislature  a  plan  for  the  systematic  classification  of  all  the  highways 
and  townways  in  this  Commonwealth  into  two  or  more  of  the  fol- 
lowing three  classes: — 

Class  i.  State  roads,  to  be  controlled  and  maintained  wholly  by 
the  State. 

Class  2.  District  roads,  to  be  controlled  and  maintained  by  the 
State,  but  the  expense  thereof  to  be  borne  by  the  towns  and  cities 
of  the  districts  in  which  said  road  shall  lie,  and  the  State,  in  such 
proportions  as  said  Board  shall  apportion. 

Class  3.  Town  roads  to  be  controlled  and  maintained  as  now 
provided  by  law. 

The  construction  of  new  roads,  of  the  three  classes  above  speci- 
fied, to  be  done  as  follows: — 

Class  i.  State  roads,  to  be  laid  out  and  built  by  the  State, 
through  the  Board  of  Highways  and  Bridges. 

Class  2.  District  roads,  to  be  laid  out,  etc.,  by  the  county  com- 
missioners, as  now  provided,  but  the  board  to  have  the  final  ap- 
proval or  disapproval  of  the  proposed  plans  and  profiles  for  said 
road,  and  also  to  have  the  charge  and  superintendence  of  their  con- 
struction. 

Parties  aggrieved  by  the  refusal  or  neglect  of  county  commis- 
sioners to  lay  out  a  road,  to  have  the  right  to  appeal  to  the  Board 
of  Highways. 

Class  3.  Town  roads,  to  be  laid  out  and  constructed  as  now 
provided  by  law. 

SEC.  8.  The  paying  of  road  taxes  by  labor  is  hereby  abolished, 
and  all  road  taxes  are  hereafter  to  be  paid  in  cash. 

SEC.  9.  Board  shall  have  the  special  charge  and  superintend- 
ence, subject  to  the  laws  and  resolves  of  this  Commonwealth,  of 
all  the  highways  and  bridges,  and  the  public  works  appertaining 
thereto,  which  are  or  shall  be  executed  or  maintained,  wholly  or  in 
part  by  this  Commonwealth.  They  shall  also  perform  such  other 
duties  as  may  be  required  of  them  by  the  general  court  or  the  Gov- 
ernor and  Council. 

SEC.  10.  Whenever  any  highway  or  bridge,  or  public  work  ap- 
pertaining to  these  two,  shall  come  partly  within  the  province  of 
this  Board,  and  partly  within  that  of  any  other  State  board,  already 
constituted,  then  such  subject  shall  be  discussed  and  decided  upon 
in  a  joint  convention  or  conventions,  composed  of  equal  numbers 
of  this  and  the  said  other  State  board,  and  some  member  by  them 
chosen  as  presiding  officer. 

SEC.  ii.  All  applications  or  propositions  for  improvements  01 
new  works,  of  the  kind  specified  in  section  nine  as  coming  within 
the  province  of  this  Board  of  Highways  and  Bridges,  and  intended 
to  be  laid  before  the  legislature,  shall  hereafter  be  first  made  to  this 


THE  SCIENCE  OF  ROAD  MAKING. 


Board.  Upon  receiving  such  application,  Board  shall  investigate 
same,  and  if  they  find  such  work  necessary  and  proper,  shall  thus 
report  to  the  legislature,  with  an  estimate  of  the  expense  thereof; 
if  they  do  not  approve  of  such  application,  they  shall  report  the 
reasons  for  their  disapproval. 

The  Board  may  also,  in  like  manner,  recommend,  whenever 
they  think  proper,  any  improvements  of  the  kind  above  specified, 
though  no  application  has  been  made  therefor. 

SEC.  12.  It  shall  be  the  duty  of  the  Board  to  procure  for  the 
legislature  full  plans  and  estimates  of  contemplated  works  or  im- 
provements when  so  ordered  by  the  legislature. 

SEC.  13.  Whenever  any  work  shall  have  been  authorized  or 
ordered  by  the  general  court  and  the  money  appropriated  therefor, 
Board  shall  advertise  for  proposals  for  doing  said  work ;  plans  and 
specifications  of  the  same  first  to  be  placed  on  file  in  office  of  Board, 
which  plans  and  specifications  shall  be  open  to  public  inspection ; 
advertisement  to  state  work  to  be  done  and  to  be  published  ten  (10) 
days  at  least.  The  bids  shall  be  sealed  bids,  directed  to  Board  and 
accompanied  by  bond  to  the  Commonwealth  signed  by  bidder  and 
two  responsible  sureties,  in  sum  of  two  hundred  ($200)  dollars, 
conditioned  he  shall  do  the  work  if  awarded  to  him,  in  case  of  his 
default  to  do  so,  forfeits,  &c.  Bids  to  be  opened  at  time  and  place 
mentioned  in  advertisement. 

SEC.  14.  All  contracts  shall  be  awarded  to  the  lowest  responsi- 
ble bidder  and  who  sufficiently  guarantees  to  do  work  under  super- 
intendence and  to  satisfaction  of  Board ;  provided  that  the  contract 
price  does  not  exceed  the  estimate  or  such  other  sum  as  shall  be 
satisfactory  to  Board.  Copies  of  contracts  to  be  filed  with  state 
auditor. 

SEC.  15.  Board  reserves  right  in  contracts  to  decide  questions  as 
to  proper  performance  of  work  and  meaning  of  contracts;  in  case 
of  improper  construction  may  suspend  work  andrelet  the  same;  or 
order  entire  re-construction;  or  may  relet  to  other  contractors  and 
settle  for  work  done,  &c.  In  cases  where  contractor  properly  does 
work,  Board  may  in  their  discretion  as  work  progresses,  grant  to 
said  contractors  estimates  of  amount  already  earned,  .reserving 
fifteen  per  cent,  therefrom,  which  shall  entitle  holder  to  receive 
amount,  all  other  conditions  being  satisfied. 

SEC.  1 6.  In  case  prosecution  of  any  public  work  be  suspended, 
or  bid  be  deemed  excessive,  or  bidders  be  not  responsible,  Board 
may,  with  written  approval  of  governor,  where  the  urgency  of  the 
case,  or  interests  of  the  Commonwealth  require  it,  employ  work- 
men to  perform  or  complete  any  work  ordered  by  the  legislature : 
provided,  that  the  cost  and  expense  shall  in  no  case  exceed  the 
amount  appropriated  for  the  same. 

SEC.  17.  All  supplies  of  materials,  &c.,  when  costing  over  five 
hundred  ($500)  dollars,  to  be  purchased  by  contract,  subject  to  same 
conditions  as  letting  out  work. 


64 


THE  SCIENCE  OF  ROAD  MAKING. 


SEC.  1 8.  Whenever  Board  think  necessary,  for  interests  of  the 
Commonwealth,  to  protect  same  from  damage  or  loss,  shall  report 
thus  to  governor  and  council  and  reasons  for  same,  asking  power 
to  give  contracts  without  notice  required  above,  and  governor  and 
council  may  grant  request,  provided  three-fourths  vote  for  it. 

SEC.  19.  Whenever  Board  is  of  opinion  a  work  may  be  done 
better  without  a  contract,  shall  so  report  to  legislature,  and  they 
shall  procure  machinery,  materials,  &c.,  hire  workmen,  &c.,  to  do 
said  work,  whenever  so  authorized  by  the  legislature. 

SEC.  20.  All  contracts  and  bonds  by  Board  to  be  in  the  name  of 
the  Commonwealth. 

SEC.  21.  No  member  of  the  Board  to  be  interested  in  any  con- 
tract; all  contracts  made  with  any  member  interested,  governor 
may  declare  void,  and  shall  remove  such  member  so  interested  from 
office.  It  is  the  duty  of  every  member  of  the  Board  and  every 
officer  of  the  Commonwealth  to  report  any  such  delinquency,  if 
discovered. 

SEC.  22.  Board  shall  be  empowered  to  employ  such  engineers, 
clerks  or  other  assistants,  as  shall  be  provided  for  by  the  legislature. 

SEC.  23.  Board  shall,  on  or  before  every  year,  submit 

to  the  auditor,  by  him  to  be  presented  to  the  legislature  with  his 
annual  estimate,  a  statement  of  the  repairs  and  new  work  needed 
for  the  current  year,  and  of  the  sums  required  by  the  Board  there- 
for; report  to  be  in  detail;  all  sums  appropriated  therefor  to  be  in- 
cluded in  the  annual  tax-levy. 

SEC.  24.  All  moneys  to  be  paid  to  any  person  out  of  moneys  so 
raised,  shall  be  certified  by  president  of  Board  to  auditor,  who  shall 
draw  warrant  on  treasurer  therefor,  stating  to  whom  payable  and 
to  what  fund  chargeable;  such  warrant  to  be  countersigned  by 
president  of  Board. 

SEC.  25.  Board  to  keep  accounts,  showing  moneys  received  and 
spent,  clearly  and  distinctly,  and  for  what  purpose.  Accounts  to  be 
always  open  for  inspection  of  auditor  or  any  committee  appointed 
by  the  legislature. 


THE  CONSTRUCTION  AND  MAINTENANCE  OF 
ROADS: 


The  writer  wishes  to  give  the  Society  some  statistics  and  suggestions 
regarding  the  construction  and  maintenance  of  wheelways,  partly  drawn 
from  his  experience  in  charge  of  such  work  and  from  observation  and 
information  acquired  in  this  country,  and  recently  in  London  and  Paris. 

EARTH  ROAD?. 

In  the  construction  of  an  earth  or  gravel  road  the  effort  should  be  to 
keep  the  material  near  the  surface  as  nearly  homogeneous  as  possible, 
that  the  surface  may  be  uniformly  hard.  The  upper  layers  at  least  should 
be  thoroughly  rolled  in  thin  layers,  with  sprinkling,  if  the  material  is  too  dry 
to  pack  well.  The  most  efficacious  rollei  for  this  purpose  is  of  two  sets  of 
disks,  one  about  eight  inches  less  in  diameter  than  the  other,  placed  alter- 
nately on  the  axis  of  the  roller.  It  is  understood  that  the  cost  of  com- 
pacting reservoir  embankments  with  this  roller  is  about  three-fourths  of  a 
cent  per  cubic  yard.  The  writer  has  never  seen  it  used  in  road  mainte- 
nance. 

When  the  soil  is  sandy  but  little  can  be  done  besides  covering  it  with 
some  more  tenacious  material.  Clay,  or  clay  hard-pan,  is  the  best,  unless 
a  sufficient  coat  of  gravel  can  be  afforded.  Even  a  clay  road,  if  the  traffic 
is  not  too  heavy,  can  be  kept  in  a  firm  state  by  careful  and  continuous 
maintenance  ;  a  coat  of  sand  or  hard-pan  is,  of  course,  desirable. 

The  plan  often  pursued  of  repairing  roads  once  or  twice  a  year  is  not 
economical,  for  the  dilapidations  increase  in  a  heavy  ratio  after  they  com- 
mence. 

A  fair  average  for  re-forming  a  mile  of  old  road  30  feet  wide  between 
gutters,  where  the  material  was  mostly  cast  from  the  sides,  was  164  days, 
10  hours  each,  of  laborers,  and  two  days  of  a  double  team  hauling  earth, 
carrying  away  stones,  and  moving  tool-box.  The  use  of  a  railroad  scraper 
would  have  been  an  economy. 

Maintenance  is  most  economically  performed  by  double  teams,  with 
hones  or  scrapers,  rollers,  and  the  watering-cart  in  dry  weather.  The 
hone  or  scraper  is  often  an  oak  plank,  2  inches  thick,  10  inches  broad,  and 

*By  Edward  P.  North,  C.  E.,  Member  of  the  Society,  read  before  the  American  Society  of  Civil 
Engineers,  April  16th,  1879, 


66     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

9  or  10  feet  long,  shod  on  its  lower  edge  with  a  %-mch  plate  of  iron, 
Drawn  vertically  along  the  road  either  by  a  tongue  or  a  chain — in  the  first 
case  it  has  two  handles  like  plow  handles— in  the  second  it  has  a  vertical 
handle,  and  the  earth  is  dumped  by  pushing  it  forward  ;  a  piece  of  plank 
about  3  feet  long  being  fastened  behind,  by  riding  on  which  the  driver  can 
regulate  the  amount  of  earth  moved.  These  are  drawn  over  the  road,  in- 
clined 7  or  10  degrees  from  a  perpendicular,  to  the  line  of  travel.  So  that, 
besides  filling  small  depressions,  they,  to  a  slight  extent,  scrape  the  earth 
to  or  from  the  centre  of  the  road.  There  are  also  some  patented  machines, 
combining  a  scraper  and  roller  in  a  frame,  which  are  said  to  be  very  effec- 
tive. 46,000  to  47,000  square  yards  can  be  covered  in  a  day,  while  not 
more  than  2,300  can  be  put  in  order  if  the  road  is  rutted  and  gullied. 
While  hones  are  of  little  use  on  muddy  roads,  they  are  effective  just  as  it 
is  drying. 

The  ordinary  type  of  roller  has  6  rings,  the  whole  length  being  6  feet, 
and  weighing  about  2  tons,  with  frames  that  will  hold  \%  tons  of  stone. 
A  better  is  of  2  rings,  3  feet  long,  also  weighing  2  tons.  Another  is  figured 
in  Clemens  Herschel's  Prize  Essay  on  Roads,  and  in  General  Gilmore's 
Roads,  Streets  and  Pavements. 

The  roller  should  follow  the  re-forming  of  the  roadbed,  whether  with 
hones,  shovels,  or  the  ordinary  railroad  scraper. 

The  writer  has  rolled  earth  roads  with  a  1 5-ton  steam  roller,  but  not 
enough  to  be  certain  as  to  its  economic  value ;  where  the  soil  contained  a 
fair  amount  of  clay,  the  roadbed  was  left  very  hard,  and  wore  well. 

A  water  cart  holding  60  cubic  feet  will  water  830  to  860  square  yards, 
and  can  be  drawn  by  an  ordinary  team  over  any  road  that  is  worth 
watering.  Two  sprinklings  per  day  will  keep  the  road  in  good  condition, 
though  not  free  from  dust  in  hot  weather  or  high  winds,  if  there  is  much 
traffic  on  the  road.  Sprinkling  is  the  only  thing  that  will  keep  a  road 
from  breaking  up  in  long  continued  dry  weather. 

The  treatment  of  gravel  roads  compacted  either  by  traffic  or  horse 
rollers,  differs  very  little  from  that  pursued  with  earth  roads.  When  the 
gravel  is  over  i  inch  in  diameter,  it  is  almost  impossible  to  keep  the  road- 
bed from  breaking  up  when  dry,  and  %  inch  would  be  a  better  size,  unless 
continuous  watering  can  be  depended  on  in  dry  weather.  Small  gravel 
(and  the  same  remark  applies  to  metal  for  Macadam)  makes  a  pleasanter 
road  for  travel,  and  can  be  more  easily  kept  in  order. 

St.  Nicholas  Avenue,  which  will  be  mentioned  further  on,  was  made 
from  nearly  clean  Roa  Hook  gravel,  by  the  aid  of  a  1 5-ton  roller,  but 
with  a  horse  roller  it  will  be  necessary  to  add  clay,  loam  or  some  softer 
material,  to  any  hard  or  clean  gravel  to  act  as  binding.  W.  H.  Grant, 
Member  of  the  Society,  in  his  valuable  description  of  the  roads  of  Cen- 
tral Park,  says  of  Roa  Hook  gravel,  "  it  being  more  than  ordinarily 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    67 

clean  and  hard,  bears  an  intermixture  or  adulteration  of  20  to  25  per  cent 
of  inferior  material  to  perfect  its  binding  properties."  These  roads 
have  a  foundation  of  rubble  stone,  not  so  firmly  packed  as  Telford 
specified,  covered  with  quarry  chips  and  hard-pan,  which  was  rolled 
with  2-horse  rollers,  6  feet  long.  4<  This  is  thoroughly  done  to  prevent 
the  gravel  filling  the  cavities  of  the  rubble  bottom,  so  that  its  cellular 
character  may  remain  unimpaired  to  facilitate  drainage."  The  gravel 
was  applied  to  two  or  three  successive  layers,  making  a  depth  of  4  to  6 
inches.  Each  layer  was  rolled  with  a  2-horse  roller,  and  the  last  \\ith  one 
weighing  6%  tons,  5  feet  long,  giving  217  Ibs.  per  inch  pressure.  These 
roads,  which  were  thoroughly  underdrained  and  side  guttered,  have  long 
been  famous  for  their  excellence  ;  they  are  pleasanter  for  light  travel  than 
Macadam,  and  are  easily  kept  in  repair,  except  in  wet  weather,  when  they 
become  muddy,  and  when  neglected,  the  larger  pebbles  make  a  rough 
road  for  buggy  riding. 

For  horse  rolling  binding  should  be  applied  as  sparingly  as  possible, 
and  on  the  last  layer,  after  it  has  been  compacted,  simply  as  a  glaze  to 
hold  the  stone  ;  if  it  contains  clay,  it  should  be  as  moist  as  possible,  not. 
to  stick  to  the  roller. 

The  so-called  Tompkins  Cove  gravel,  which  is  much  used  for  en- 
trance drives  to  gentlemen's  places  about  New  York,  is  a  broken  lime- 
stone, apparently  of  the  cement  series.  It  is  usually  spread  over  the 
road,  and  compacted  by  the  wheels.  The  darker  colored  stone  is  very 
pleasant  to  the  eye,  and  it  readily  makes  a  smooth  wheelway  singularly 
free  from  either  mud  or  dust,  even  when  subjected  to  rather  heavy  traffic, 
though  it  is  too  friable  for  economical  use  in  such  situations.  Its  per- 
formance is  so  different  from  that  of  the  ordinary  limestones  that  an. 
analysis  is  appended  : 

Lime  ..   60.20 

Alumina 11. '22 

Silica 6.13 

Magnesia 10.45 

Carbonic  Acid 8.00 

Water 4.00 

100.00 

MACADAM. 

Roadways  surfaced  with  broken  stone  have  been  in  use  for  a  long 
time,  but  Macadam,  about  the  end  of  the  last  century,  systematized  their 
construction  and  maintenance,  effecting  such  an  improvement  in  English 
roads  that  his  name  seems  indissolubly  connected  with  roads  of  this  class. 
His  plan  seems  to  have  been  essentially  to  have  a  well  drained,  uniform 
road  bed  for  the  reception  of  small,  clean  stone  of  uniform  quality  applied 
in  thin  courses,  deprecating  any  addition  of  earth,  clay,  chalk,  or  other 
matter  that  will  imbibe  water  and  be  affected  by  frost,  under  the  pretense 
of  binding  it. 


68    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

He  held  that  a  surface  of  an  inch  square  or  a  stone  6  ounces  in  weight 
was  of  the  maximum  size  for  road  metaling,  anything  larger  than  that 
being  mischievous,  and  that  10  inches  of  solid  Macadam  was  sufficient  to 
carry  any  load,  rather  preferring  a  soft  substratum,  saying  that  the  cost  of 
maintenance  on  a  morass  was  to  the  cost  on  a  rocky  foundation  in  the 
ratio  of  5  to  7. 

Telford  differed  from  Macadam  in  his  views,  how  much  may  be  best 
seen  from  one  of  his  specifications  taken  from  Parnell's  Treatise  on 
Roads:  London,  1833,  p.  147  <?/.  seq. :  "Upon  the  level  bed  prepared  for 
the  road  materials  a  bottom  course  or  layer  of  stones  is  to  be  set  by  hand 
in  the  form  of  a  close,  firm  pavement.  They  are  to  be  set  on  their  broad- 
est edges  lengthwise  across  the  road,  and  the  breadth  of  the  upper  face  is 
not  to  exceed  4  inches  in  any  case.  All  of  the  irregularities  of  the  upper  part 
of  the  said  pavement  are  to  be  broken  off  by  the  hammer,  and  all  the  inter- 
stices to  be  filled  with  stone  chips  firmly  wedged  or  packed  by  hand,  with  a 
light  hammer.  The  middle  18  feet  of  pavement  is  to  be  coated  with  hard 
stone  as  nearly  cubical  as  possible,  broken  to  go  through  a  2>^-inch  ring, 
to  the  depth  of  6  inches,  4  of  these  6  inches  to  be  first  put  on  and 
worked  by  traffic,  after  which  the  remaining  2  inches  can  be  put  on.  The 
work  of  setting  the  paving  stones  must  be  executed  with  the  greatest 
care,  and  strictly  according  to  the  foregoing  directions,  or  otherwise  the 
stones  will  become  loose,  and  in  time  may  work  up  to  the  surface  of  the 
road.  When  the  work  is  properly  executed  no  stone  can  move :  the 
whole  of  the  materials  to  be  covered  by  i%  inches  of  good  gravel,  free 
from  clay  or  earth."  Of  which  Parnell  says,  "  The  binding  which  is  re- 
quired to  be  laid  on,  on  a  new-made  road,  is  by  no  means  of  use  to  the 
road,  but,  on  the  contrary,  injurious  to  it.  This  binding  by  sinking  be- 
ween  the  stones  diminishes  the  absolute  solidity  of  the  surface  of  the  road, 
lets  in  water  and  frost,  and  contributes  to  prevent  the  complete  consolida- 
tion of  the  mass  of  the  broken  stones." 

As  regards  the  foundation,  Macadam  seems  to  have  the  engineers  of 
France  and  England  mostly  on  his  side.  In  this  country,  it  is  believed 
engineers  generally  prefer  a  Telford  foundation.  Neither  Macadam  or 
Telford  used  a  roller,  both  depending  on  the  grinding  action  of  the 
wheels  of  wagons  to  compact  their,  roads  ;  and  it  was  probably  to  lessen 
the  brutal  pulling  through  loose  metal  that  Telford  used  his  coating  of 
gravel. 

Road  rolling  was  first  brought  prominently  before  English  readers  by 
Sir  John  F.  Burgoyne,  in  a  paper  written  in  1843  (which  is  reproduced 
by  Law  &  Clark).  And  the  best  American  practice  very  fully  indorses 
his  views.  He  recommends  a  weight,  as  the  greatest  attainable,  of  261 
pounds  per  inch  run  of  roller,  the  use  of  stone  dust  or  sharp  gravel  for 
binding  and  watering.  His  opening  sentence,  "  the  importance  of  rolling 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.     69 


roads,  either  newly  constructed  or  when  subjected  to  extensive  repairs, 
seems  never  to  have  been  duly  appreciated,"  is  still  true  in  England,  for 
the  writer  saw  loose  stone  kicking  about  Great  George  street,  in  front  of 
the  Institution  of  Civil  Engineers,  for  over  a  month. 

It  may  here  be  said  that  writers  on  roads  have  not  always  kept  the 
differences  between  the  possibilities  of  construction  of  the  three  types  of 
Macadam  roads  (viz.,  traffic  made,  horse  rolled  and  steam  rolled)  suffi- 
ciently before  their  readers.  The  grinding  action  of  wheels  will  pack  the 
hardest  stones  of  proper  size,  and  make  a  firmer  roadbed  than  if  a  softer 
material  is  used  for  binding,  but  about  one-third  of  the  material  is  worn 
out  in  the  operation,  to  say  nothing  of  the  wear  on  horses  and  wagons. 
On  account  of  the  digging  action  of  the  horses'  feet  when  drawing  heavy 
rollers,  horse  rollers  will  only  compact  and  bind  the  softer  rocks,  without 
the  aid  of  binding  material,  and  no  steam  roller  known  is  heavy  enough 
to  bind  trap  and  the  harder  granites,  without  such  aid. 

The  only  circumstance  that  can  justify  an  engineer  in  depending  on 
traffic  to  make  his  road  (except  in  the  case  of  small,  thin  patches)  is  an 
inability  to  procure  a  roller  ;  and  then  the  material  should  be  applied  in 
very  thin  layers,  for,  in  addition  to  the  waste  of  material,  the  cost  of  rak- 
ing and  leveling  a  new  road  will  nearly  equal  the  cost  of  horse  rolling, 
the  surface  will  never  be  as  good  ;  and,  as  dung  and  dust  will  be  ground 
in  with  the  stone,  it  will  be  more  affected  by  wet  and  frost.  In  addition, 
as  a  road  is  made  for  economy  and  convenience  of  transportation,  the 
damage  to  horses  and  vehicles  should  not  be  allowed,  even  if  it  made 
a  better  road. 

While  a  horse  roller  will  make  a  much  better  road  than  traffic  will* 
it  is  inferior  to  a  road  rolled  by  steam  rollers,  for  about  260  pounds  per 
inch  run  of  roller  seems  to  be  the  greatest  weight  practically  attainable 
by  horse  rollers,  which  is  not  sufficient  to  make  a  road  of  trap  and  the 
harder  stones,  without  the  use  of  some  softer  materials  as  binding,  which 
presents  the  objections  stated  by  Parnell,  even  under  the  most  careful 
system  of  application. 

With  a  steam  roller  the  weight  applied  can  be  made  equal  to  the 
requirements.  The  horses'  feet  do  not  cut  up  the  metal  almost  as  fast 
as  it  is  arranged  and  compacted  by  the  roller.  Hard  binding  can  be  used, 
making  the  roadbed  nearly  homogeneous  and  impervious  to  water,  pre- 
venting movement  of  the  stones  on  each  other.  Lastly,  the  frictional 
action  of  the  driving  wheels  arranges  and  compacts  the  stones  better 
than  a  greater  rolling  weight  does,  making,  in  fact,  an  entirely  different 
wheelway  in  its  wearing  and  sanitary  aspects. 

The  best  horse-rolled  road  known  to  the  writer  is  the  Southern  Boul- 
evard, built  by  Wm.  E.  Worthen,  Member  of  the  Society.  The  earth 
was  compacted  by  rolling,  on  which  2^  inch  trap  was  placed  in  one 


70     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

6-inch  and  one  4-inch  layer,  when  both  layers  were  compressed  as  far  as 
possible  by  the  use  of  2-horse  rollers  ;  2^  inches  of  screenings  were 
spread  over  and  rolled  in.  As  water  was  not  easily  attainable  on  the 
line  of  the  road,  the  screenings  were  thoroughly  wet  before  they  were 
carted  to  the  road.  This  wheehyay,  which  was  fourteen  or  fifteen  feet 
wide,  stood  seven  years,  almost  entirely  without  care,  under  a  heavy  cart- 
ing traffic  and  a  good  deal  of  light  driving.  But  the  road  was  never  as 
solid  as  those  made  with  steam  rollers  and  properly  puddled,  opening  more 
with  the  frost,  and  having  more  loose  stones  on  it. 

The  writer  built  some  horse-rolled  road  on  an  old  Macadam  road 
which  was  substantially  worn  out.  The  material  was  a  syemtic  gneiss 
quite  hard,  and  broken  by  hand  to  pass  through  a  2-inch  ring.  It  was 
generally  laid  on  6  inches  thick,  in  one  course,  though  where  the  old  metal 
wras  mostly  gone,  two  layers  of  stone  were  used.  The  rollers  were  6  feet 
long,  weighing  about  2  tons  light  and  3%  loaded.  They  wrere  used  with 
2  horses  light  and  4  horses  heavy.  The  stones,  which  were  broken  on  the 
side  of  the  road,  were  handled  with  lo-tined  forks,  the  tine  14  inches  long, 
iX  inches  apart,  known  as  "tanners'  forks."  These  forks,  with  a  little 
care  on  the  part  of  the  laborer,  left  nearly  all  the  dust  and  small  stone 
behind  (the  average  wear  of  tines  was  one  inch  for  300  cubic  yards 
handled),  so  that  the  stones  went  into  the  road  fairly  clean,  where  they 
were  rolled  ;  the  shoulders  being  at  the  same  time  made  up  with  good 
earth,  until  they  were  fairly  compact,  when  the  dust  and  small  stones 
left  by  the  forks  were  spread  on  the  surface,  which  was  again  covered 
with  about  ^  of  an  inch  of  preferably  clayey  soil,  where  it  was  procurable, 
which  was  rolled  thoroughly.  If  the  binding  was  sufficiently  damp,  the 
road  stood  very  well,  showing  few  loose  stones  ;  but  when  it  was  too  dry 
or  the  earth  was  washed  into  the  body  of  the  metal  by  heavy  rains,  the 
work  was  not  at  all  satisfactory. 

The  labor  account  per  mile  of  wheelway,  14  feet  wide,  equal  to  £,213 
square  yards,  on  which  1,260  cubic  yards  of  broken  stone  were  placed, 
was  as  follows,  the  days  being  10  hours  each  :  Spreading  and  forming 
material  and  loading  dirt  for  shoulders  and  binding,  with  sweeping  the  old 
Macadam  clean,  but  no  picking,  229.5  days'  labor.  Twenty-four  days 
were  occupied  rolling,  13.2  with  2-horse  and  10,8  with  4-horse  teams. 

This  road,  with  the  shoulders,  was  18  feet  wide,  and  the  teams  trav- 
eled at  the  rate  of  2  miles  per  hour ;  allowing  90  per  cent,  of  the  time 
as  productive,  the  roller  passed  144  times  over  the  surface.  The  mean 
weight  of  the  rollers  per  inch  run  was  only  75  Ibs.,  and  the  maximum 
100  Ibs.,  a  weight  altogether  too  light  for  either  economical  or  thorough 
work. 

One  end  of  this  road  was  on  a  hill,  with  a  rise  of  no  in  1,500  feet ; 
the  maximum  grade  being  at  a  rate  of  8  per  100.  It  was  not  judged  ad- 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS,    yi 


visable  to  depend  on  natural  moisture  for  the  binding,  and  a  steam  pump 
was  procured,  by  the  aid  of  which  the  metal  was  made  thoroughly  wet 
before  the  binding  was  applied.  The  binding  used  on  the  hill  was  a  light 
loam  ;  but  considering  the  grade,  the  finished  wheelway  was  as  good  as 
when  heavier  loam  had  been  used,  relying  on  the  moisture  in  it. 

In  England  there  does  not  seem  to  be  any  well-established  system  of 
road  making.  Some  of  the  borough  surveyors  apparently  do  not  believe 
in  any  rolling  at  all ;  others,  after  caref  nlly  picking  up  the  old  roadbed, 
put  on  the  stones,  and  after  more  or  less  traffic  has  passed  over  it,  put  on 
a  5-ton  roller  5  feet  long,  drawn  by  4  to  6  horses.  The  binding  called 
"  h°ggm»"  which  is  a  loam  with  coarse  sand  and  gravel  in  it,  is  apparently 
not  always  applied  in  the  case  of  repairs.  Appendix  No,  i  is  referred  to 
for  specifications  for  a  new  road. 

The  repairs  of  the  wheelway  of  the  Victoria  Embankment  were  made 
by  first  thoroughly  picking  up  the  old  roadbed  and  then  coating  it  with 
clean  Guernsey  granite,  hand  broken,  to  go  through  a  2^  inch  ring, 
entirely  free  from  dust  and  debris,  and  nearly  so  from  small  stone. 
Guernsey  granite  is  about  as  hard  as  a  trap.  It  was  rolled  with  1 5-ton 
Aveling  &  Porter's  rollers.  When  compacted,  hoggin  was  added  in  suffi- 
cient quantity,  and  with  enough  water  to  flush  the  material  into  all  the 
interstices  and  leave  a  surplus  about  the  thickness  of  grout  on  the  surface, 
which  was  swept  with  brooms  in  front  of  the  rollers.  The  same  system 
was  employed  at  Russell  Square  and  Bedford  Place. 

This  did  not  make  a  good  Macadam  road  ;  the  hoggin  acted  as  a 
lubricant,  allowing  the  stones  to  work  on  each  other  under  the  traffic. 
There  were  loose  stones  on  the  road  ;  five  weeks  after  the  road  was  com- 
pleted, a  kick  would  move  the  stones  in  front  of  it  for  fully  a  foot ;  when 
the  surface  was  drying,  the  outlines  of  many  of  the  stones  could  be  seen 
by  the  cracks  in  the  mud  covering  them  ;  the  angles  of  the  stones  were 
already  wearing  off,  and  after  a  rain,  on  sweeping  the  road,  the  gutters 
were  filled  with  mud  4  to  6  feet  wide. 

It  was  said  that  dissatisfaction  was  felt  with  this  system,  and  during  the 
past  summer  an  effort  was  made  to  make  a  road  simply  by  rolling,  without 
the  aid  of  any  binding.  The  success  was  no  greater  than  that  of  Mr. 
Grant,  20  years  ago,  in  the  Central  Park. 

In  Liverpool  a  mixture  of  broken  stone  and  coal  tar  pitch  is  laid — 
one  ton  of  pitch  that  will  just  run  at  100°  F.,  is  mixed  with  70  galls  of 
dead  oil,  and  added,  hot,  to  5  cubic  yards  of  stone.  The  stone  is  dry, 
but  not  heated  ;  the  mixture  is  rolled  with  a  hand  roller  in  short  lengths. 
The  surface  is  very  good,  making  a  favorite  road  for  bicycle  riders, 
and  it  can  be  swept  without  danger  of  dislodging  stone,  but  it  does  not 
seem  to  have  the  wearing  qualifies  of  a  well  puddled  trap  road.  Some 
laid  three  years  in  Basnat  street,  now  requires  pretty  extensive  repairs. 


72     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 


In  Scotland,  a  concrete  has  been  used  with  Portland  cement,  for  bird- 
ing;  the  surface  was  very  good,  but  when  the  road  commenced  to  break 
it  went  to  pieces  very  fast. 

M.  Malo  speaks  of  the  Macadam  in  Paris  as  follows  :  "  Day  by  day 
they  try  with  incalculable  efforts  to  perfect  Macadam.  They  have  per- 
fected their  watering  in  summer  and  sweeping  in  winter  ;  they  have  sub- 
stituted, at  great  cost,  granite  in  place  of  limestone  ;  they  have  multiplied 
their  road  laborers  ;  each  morning  the  devastacions  of  the  day  before  are 
repaired  with  incredible  rapidity,  but  when  the  stream  of  traffic  again  covers 
the  street,  the  rcourge  (fleau)  recovers  its  rights,  and  during  300  days  of  the 
year  the  roadway  becomes  an  ocean  of  mud  or  a  mass  of  infected  dust," 
In  other  words,  a  poor  system  of  construction,  but  probably  the  most 
thorough  system  of  maintenance  to  be  found  anywhere.  A.  Debauve,  in 
his  "Manuel  de  1'Ingenieur,"  after  speaking  of  the  immense  capital  invested 
in  the  old  Roman  roads,  says  :  "  The  tendency  now  is  to  have  the  thick- 
ness only  that  which  is  necessary  for  resistance,  to  suppress  the  founda- 
tion, and,  in  one  word,  to  economically  establish  the  roadways  and  maintain 
them  afterward  in  a  fit  state  by  incessant  repairs,  which  the  ancients  did 
not  know  of." 

In  Paris  the  Macadam  roads  are  composed  of  water-worn  flint  pebbles, 
which  are  compacted  by  ramming  with  a  rammer  8  inches  in  diameter, 
weighing  70  Ibs.,  and  horse  rolling  with  the  aid  of  sand  and  water,  meu- 
liere — a  kind  of  burr  mill  stone — and  porphyry,  the  two  latter  are  gener- 
ally steam  rolled.  These  materials  are  used,  according  to  Debauve,  in  the 
following  proportions,  viz. :  flint,  10  per  cent. ;  meuliere,  67  per  cent.,  and 
porphyry,  23  per  cent. 

Macadam  roads  in  Paris,  as  in  London,  are  the  roads  of  luxury.  On 
many  streets,  the  centre,  for  a  width  of  19  feet,  is  covered  with  Macadam^ 
while  the  sides,  for  a  width  of  13  feet  each,  are  paved  with  stone  sets  or 
asphalte.  The  Avenue  des  Champs  Elysees,  Place  Concorde,  and  some 
of  the  Quais  are  of  flint ;  other  of  the  Quais  and  Rue  de  Rivoli  are  of 
harder  stone,  while  the  Avenue  de  1'Opera,  Boulevard  Haussmann,  etc., 
have  Macadam  only  in  the  middle. 

The  French,  who  use  the  Gellerat  roller  in  Paris,  specify  a  maximum 
weight  of  448  Ibs.  per  inch  run,  and  a  maximum  speed  of  2.3  miles  per 
hour.  The  rolling  is  done  by  contract  (the  city  furnishing  the  water)  at  a 
rate  per  ton  mile,  varying  from  1 5.26  co  7.63  cents,  according  to  the  amount, 
with  an  increase  of  one-third  in  price  where  the  grade  exceeds  6  per  cent. 

The  thickness  of  metal  rolled  varies  from  12  inches  on  new  roads  to 
2  inches  on  old.  It  is  maintained  that  the  work  of  compacting  a  cubic 
yard  of  the  same  stone  is  independent  of  the  thickness  when  that  varies 
between  2  and  6  inches,  and  is  from  2.7  to  3.27  ton  miles  per  cubic  yard. 

From  a  table  (p.  308)  in  the  notice  of  the  objects,  etc.,  exhibited  by 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    73 

the  city  of  Paris  at  the  Exhibition  of  1878,  it  is  seen  that  the  mean  weight 
per  inch  run  of  the  steam  rollers  is  448  and  336  Ibs.,  and  for  the  horse 
rollers  263  Ibs.  Also  that  the  ton  miles  necessary  to  make  a  square  yard 
of  porphyry  wheelway,  or  to  compact  a  cubic  yard  of  the  same  metal,  are 
as  follows  :  the  mean  for  the  two  models  of  machines  weighing  448  Ibs. 
per  inch  run  was,  per  square  yard,  with  thickness  of  3.9  inches,  0.41  ton 
miles  ;  while  for  the  roller  of  336  Ibs.,  with  a  thickness  of  2.8  inches,  0.234 
ton  miles  were  required,  or  3.78  and  2.99  ton  miles  per  cubic  yard  respect- 
ively ;  and  for  horse  rollers,  where  the  thickness  was  2.6  inches,  the  ton 
miles  required  were  0.194  per  square  yard  and  2.69  per  cubic  yard.  The 
amounts  consolidated  per  ton  per  hour  are  in  the  following  proportions  i 
467  for  the  heavy  rollers,  539  for  the  light  roller  and  297  for  the  horse 
roller,  and  the  number  of  passages  of  the  rollers  were  98.5,  75  and  92. 

It  appears  from  these  tables  that  the  smaller  weight  is  the  more  advan_ 
tageous,  and  that  horse  rolling  is  cheaper  than  steam  rolling ;  it  is  added, 
that,  on  account  of  their  superior  celerity,  the  steam  rollers  are  almost 
exclusively  employed. 

No  statement  is  made  as  to  the  relative  wear  of  stone  rolled  by  the 
different  machines. 

About  24  per  cent,  of  sand  is  used  for  binding.  The  surface  is  allowed 
to  wear  down  until  2  to  6  inches  of  metal  is  put  on. 

Repairs  were  being  made  on  Boulevard  Haussmann  by  a  5-inch  layer 
of  meuliere,  very  nicely  hand  broken  to  pass  through  a  2%-inch  ring,  free 
from  dirt  and  small  stone ;  the  roller  had  a  weight  of  360  Ibs.  per  inch- 
After  a  few  passages  had  been  made  over  the  stone,  very  clean  sand  was 
spread  on,  which  was  shortly  wet  by  a  hand  hose.  The  water  was  not  at 
first  applied  in  sufficient  quantity  to  flush  the  sand  thoroughly  into  the 
interstices,  but  the  sand  was  just  damp  enough  to  pick  up  the  stones. 
The  speed  of  the  roller  was  thought  to  be  fully  2^  miles  per  hour.  The 
binding  was  not  so  thoroughly  wet  as  on  the  Victoria  Embankment,  nor 
was  the  metal  rolled  as  much.  When  the  street  was  thrown  open  to  traf- 
fic the  consolidation  was  about  at  the  point  at  which  in  this  country  we 
would .  commence  applying  screenings,  stones  were  picked  up  by  the 
wheels,  and  a  light  kick  would  move  the  stones  for  from  i  to  i%  feet  in 
front  of  it. 

On  the  Avenue  de  1'Opera,  the  centre  of  which  is  covered  with  broken 
porphyry,  the  stones  presented  the  same  evidences  of  motion  on  each 
other,  mentioned  as  seen  on  the  Victoria  Embankment. 

In  New  York  City  there  are,  including  St.  Nicholas  avenue,  27.99 
miles  or  921.400 square  yards  of  steam-rolled  M?cadam  roads,  besides  the 
horse-rolled  roads  in  the  Central  Park  and  the  Twenty-third  and  Twenty- 
fourth  Wards,  of  which  17.75  miles  or  7 18,200  square  yards  are  on  Telford 
foundations.  They  were  commenced  in  1869,  and  mostly  finished  in  1876. 


74     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 


-  I 


The  first  had  a  5-inch  layer  of  gneiss  laid  on  the  Telford,  on  that  a 
5-inch  course  of  trap,  both  broken  to  go  through  a  2>£-inch  ring.   The  trap 

was  and  is  machine  broken,  and  the  screen- 
ings, /.  e.,  dust    and  stone    that    passes 
_c         through  a  i-inch  or  itf-'mch  aperture,  are 
used  for  binding.     At  first  it  was  held  that 

j»      ^       £      :      >>         these  should  be  used  as  sparingly  as  pos- 
lj[«  'j|       ^j      ,|     LZ         sible,  but  experience  has  shown  that  the 
roads  wear  better  and  have  less  loose  stones 
on  them  when  the  interstices  a*e  fully  filled 
with  screenings,  and  the  size  of  the  stone 
in  the  top  course  is  preferably  from  i  to 
i%  inches.     The  general  practice  now  is 
to  put  on  the  stones  in  two  courses  when 
the  thickness,  compacted,  is  6  inches  or 
more,  and  roll  the  first  course  until  it  will 
settle  no  more,  then  add  the  last  course,  and 
after  it  has  settled,  screenings  are  added,  at 
l255TW^<i»— fW   ro  ™     first  coarse  and  then  fine,  and  after  thor- 
*"*  lif$3r  j^O^jff  ^!  2     ough  rolling,  the  whole  is  puddled  by  a  co- 

pious addition  of  water.    This  is  accom- 
plished more  thoroughly  and  satisfactorily 

?§k&f£'  ^"^x^  ®         m  hot,  dry  weather.    After  the  road  is  pud- 
<        tf  ^wB^^stttSsl;  ^          died  X  to  Yt.  incn  of  screenings  are  spread 

over  it,  and  after  drying  an  hour  or  so  the 
traffic  is  turned  on. 

For  the  old  style  of  construction  Sixth 
avenue,  between  One  Hundred  and  Tenth 
street  and  Harlem  River,  may  be  taken  as 
a  type,  having  the  materials  and  courses  as 
above  mentioned.  It  was  rolled  with 
Aveling  &  Porter's  1 5-ton  rollers,  of  the  old 
pattern,  in  which  the  weight  is  nearly 
equally  divided  between  the  steering  and 
driving  wheels,  which  cover  6  feet,  giving  a 
bearing  weight  of  467  Ibs.  per  inch  run. 
As  near  as  can  be  ascertained,  24  6-10 
hours,  at  i%  miles  per  hour,  were  occu- 
pied in  rolling  1,000  square  yards,  giving 
for  the  work  done  0.553  ton  miles  per  square 


yard,  2.246  ton  miles  per  cubic  yard,  and  129.8  trips  of  the  roller  over  the 
surface. 

Avenue  St.  Nicholas,  which,  as  mentioned  above,  was  made  from  Roa 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    75 

Hook  gravel,  had  a  rubble  foundation,  and  it  was  intended  to  have  6 
inches  of  compact  gravel,  but  the  foundation  settled  so  that  in  some  in- 
stances the  gravel  is  14  inches  thick.  The  practice  was  to  lay  the  gravel 
on  and  wet  it  thoroughly  over  night.  It  was  rolled  the  next  day  until  the 
water  was  forced  to  the  surface.  A  1 5-ton  roller  was  employed  about  26 
hours  per  1,000  square  yards,  besides  some  horse  rolling.  A  little  hard 
pan  was  used  for  binding.  The  intention  was  to  make  a  road  for  fast 
driving,  but  the  surface  was  as  hard  as  that  of  a  Macadam  road,  though 
much  smoother. 

The  data  for  these  two  avenues  depend  on  the  memory  of  the  engineer 
of  the  roller,  and  are  approximate  only. 

The  Telford  Macadam  on  Fifth  avenue  has  8  inches  of  Telford,  3 
inches  of  2^  -inch  trap,  4  inches  of  2-inch  trap,  i  inch  of  coarse  screenings, 
and  one- half  inch  of  fine  screenings,  when  completed.  The  wheel  way  is 
40  feet  wide  between  curbs,  with  4  foot  gutters  on  each  side,  of  trap 
blocks. 

Mr.  F.  H.  Hamlin,  for  some  time  Engineer  in  the  charge  of  Reads  and 
Streets  in  New  York  City,  to  whom  I  am  indebted  for  these  data,  intended, 
by  the  use  of  the  \y2  inches  ot  screenings,  to  have  the  road  as  smooth  and 
pleasant  for  riding  as  Avenue  St.  Nicholas,  without  the  tendency  to  mud 
in  wet  weather.  The  work  was  let  in  two  contracts,  at  $1.30  and  $1.49 
per  square  yard.  The  average  time  employed  setting  a  square  yard  of 
Telford  was  2oj£  minutes.  Spreading  the  stone  and  screenings,  per 
square  yard,  i  2-10  minutes.  About  58  6-10  hours  rolling  were  given  per 
1,000  square  yards ;  and  the  work  done,  allowing  the  effective  speed  to 
have  been  i%  miles  per  hour,  was  1.099  ton  miles  per  square  yard,  and 
4.709  ton  miles  per  cubic  yard  of  compacted  material,  if  there  had  been  no 
settlement,  but  there  was  an  unascertained  settlement. 

These  roads  are  maintained  by  spreading  very  thin  layers  of  fine  Roa 
Hook  gravel  over  them  and  watering.  The  first  roads  were  built  with 
an  idea  that  as  small  a  quantity  of  screenings  as  possible  should  be  used, 
and  in  dry  weather  the  stones,  which  become  prominent  by  wear,  are 
liable  to  kick  out ;  the  fine  gravel  prevents  this,  and  by  retaining  water 
sprinkling  is  not  necessary  so  often.  The  fact  that  the  travel  concentrated 
near  the  gutters,  where  this  gravel,  by  the  action  of  rain,  becomes  thickest, 
in  connection  with  the  demands  of  owners  of  fast  horses,  who  wished  a 
softer  road-bed,  led  Mr.  Hamlin  to  cover  one  of  them  with  a  coating  three- 
eighths  of  an  inch  thick,  consisting  of  three  parts  of  coarse  sand  and  one 
part  of  strong  clay.  This  has  been  on  the  road  through  two  winters  and 
the  road-bed  is  still  firm,  and  it  has  been  applied  to  others. 

Under  Mr.  Hamlin's  charge  the  average  cost  of  maintaining  these 
roads  has  been  4  2-10  cents  per  square  yard  per  annum  for  the  labor  and 
material  of  road  covering,  cleaning  and  sprinkling,  with  incidental  repairs 


76     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

and  supervision.  None  of  them  have  been  resurfaced  with  broken  stone 
excepting  a  portion  of  the  Western  Boulevard,  the  first  built,  and  two  or 
three  patches  of  100  feet  or  less  in  length,  which  cost  46  cents  per  square 
yard. 

It  is  very  difficult  to  estimate  the  traffic  on  these  roads.  On  a  fine  day 
3,000  vehicles  may  pass  over  them,  while  at  other  times  there  may  be  not 
more  than  one-tenth  of  that  number. 

In  repairing  the  Southern  Boulevard,  mentioned  above,  the  trap  broken 
to  go  through  a  2-inch  ring  was  laid  on  6  inches  thick  in  one  course  ; 
38  2-10  uours'  roiling  was  given  per  1,000  square  yards.  Allowing  the 
speed  to  nave  been  i%  miles  per  hour,  the  work  done  on  it  amounted  to 
0.859  ton  miles  per  square  yard  and  5.177  ton  miles  per  cubic  yard;  201 
trips  were  rmde  over  the  surface.  The  Macadam  was  15  feet  wide,  and 
some  of  the  rolling  was  on  the  shoulders,  though  probably  not  enough  to 
affect  the  result  materially.  The  work  was  done  in  July  and  August,  and 
a  little  less  than  0.6  cubic  feet  of  water  per  square  yard  (3.5  cubic  feet  per 
cubic  yard)  were  used  in  compacting  and  puddling.  About  one-third 
screenings  were  added.  Those  portions  of  the  road  that  had  the  most 
work  done  on  them  are  now  in  the  best  form,  after  nearly  two  years  with- 
out any  care  ;  and,  generally,  the  more  thoroughly  the  trap  roads  were 
rolled  the  better  do  they  wear. 

It  should  be  understood  that  there  was  no  counter  on  the  wheels  of 
the  rollers,  and  the  speed  is  the  result  of  estimation,  interfering  with 
accuracy  in  the  estimate  cf  the  number  of  ton  miles  performed.  The 
rollers  used  fn  the  above  mentioned  works  were  1 5-ton  Aveling  &  Porter's 
(old  pattern),  and  though  they  are  understood  to  bear  equally  on  the  driv- 
ing and  steering  wheels,  the  writer  thought  the  driving  wheels  nearly  twice 
as  effective  as  the  steering  wheels. 

The  superiority  of  the  American  Macadam  roads  is  partly  due  to  the 
greater  amount  of  work  put  upon  them ;  the  binding,  which  is  of  the  same 
hard  material  as  the  metaling,  almost  completely  fills  the  interstices  between 
the  stones,  and  the  entire  mass  is  thoroughly  compacted  and  nearly  homo- 
geneous. It  is  only  while  the  frost  is  coming  out  of  the  road  in  the  spring 
that  the  stones  wear  upon  one  another  at  all.  The  process  of  puddling 
gives  a  very  smooth,  hard,  firm  surface,  resistant  alike  to  wear  and  the 
infiltration  of  water,  which  is  of  equal  advantage  to  the  stabilfty  of  the 
foundation  and  from  a  sanitary  point  of  view.  By  the  use  of  the  steam 
roller  the  stones  are  compacted  with  a  small  amount  of  wear  to  their  angles 
and  an  entire  freedom  from  mud  and  dung,  their  only  weak  point  being 
that  in  long-continued  dry  weather  the  larger  stones  are  apt  to  get  dis- 
lodged from  the  surface,  some  moisture  being  necessary  for  the  full  cohe- 
sion of  the  binding.  No  amount  of  wet  weather,  unaccompanied  by  frost, 
seems  to  injure  them,  unless  mud  works  up  through  the  foundation,  and 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    77 

their  imperviousness  under  the  most  disadvantageous  circumstances  is 
well  illustrated  by  the  practice  of  Mr.  Hamlin,  as  cited  above. 

The  English  roads  are  rolled  less,  and  the  binding,  though  cheaper  in 
cost  and  the  matter  of  rolling  and  spreading,  is,  when  thoroughly  wet,  to 
a  great  extent  an  element  of  weakness  to  the  roads,  allowing  a  large  part 
of  the  wear  to  be  internal,  and  failing  to  hold  the  stones  from  dislodgment, 
either  by  the  wheels  of  vehicles  or  the  brooms  of  the  sweepers.  When 
dry  it  can  have  neither  cohesion  nor  resistance,  its  use  being  confined  to 
the  time  it  is  slightly  damp. 

The  roads  in  Paris  seemed  to  be  less  thoroughly  compacted  than  in 
London,  but  the  binding  was  better,  and  if  it  had  been  applied  dry,  after 
the  stone  was  nearly  compacted,  and  only  wet  at  the  last  rolling,  it  would 
probably  be  more  effective.  As  it  was,  the  grain  of  the  sand  seemed  to 
have  been  broken  down  during  the  rolling  of  the  stone,  and  as,  like  the 
English  made  roads,  the  stones  move  on  one  another,  it  must  be  still  more 
thoroughly  ground  up. 

The  maintenance  of  roads  in  Paris  is  much  more  effective  than  in 
London.  It  consists  essentially  in  washing  rather  than  sprinkling  them, 
and  sweeping  the  mud  and  debris  of  the  surface  into  the  gutters,  where  it 
is  washed  with  a  copious  flow  of  water,  the  mud  and  fine  sand  going  into 
the  sewers,  the  coarser  sand  being  retained  for  use  on  the  streets.  *Most 
of  the  work  is  done  at  night  and  in  the  early  hours  of  the  morning.  While 
there  is  on  the  average  (judging  from  the  amount  of  mud  relative  to  the 
traffic)  rather  more  wear  than  in  London,  no  loose  stones  were  seen  on 
the  streets,  except  when  newly. mended,  men  apparently  being  always 
present  with  brooms,  rammers,  and  sand,  to  repair  any  place  that  showed 
signs  of  weakness.  On  the  Avenue  des  Champ  Elysees,  and  other  flint 
roads,  the  surface  was  often  swept  with  birch  brooms  having  long  and 
slender  twigs. 

In  London  the  maintenance  is  neither  so  constant  or  skillful ;  the  roads 
are  watered  in  dry  weather,  and  swept  or  scraped  in  wet,  with  an  occasional 
.addition  of  sand  or  fine  gravel. 

There  seems  to  be  no  accessible  accounts  of  the  cost  of  repairs  and 
maintenance  in  London.  W.  S.  Till,  the  Borough  Surveyor  of  Birming- 
ham, in  one  of  his  reports,  says  :  "  Mr.  Howell,  Surveyor  to  the  Vestry  of 
St.  James,  Westminster;  informs  me  that  the  cost  of  maintaining,  etc. 
the  surface  of  Regent  street,  London,  which  may  be  considered  one  of  the 
best  Macadamized  roads  in  the  Kingdom,  and  in  which  nearly  every 
description  of  pavement  has  been  tried,  is  $0.87  per  square  yard  per  annuity 
it  has,  however,  been  much  higher."  It  is  not  known  whether  Regent 
street  was  then  steam  or  horse  rolled. 

In  Paris,  the  expense  of  maintenance  had  reached  on  some  of  the  streets 
1 6  francs  per  square  meter  ($2.57  per  square  yard)  per  annum,  and  it 


78     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

was  resolved  to  pave  all  but  the  middle  23  feet,  in  streets  48  feet  wide, 
and  to  pave  narrow  streets  and  gutters,  and  in  1871  it  was  resolved  to  pave 
streets  where  the  annual  expense  of  maintenance  was  over  48  cents  per 
square  yard,  excepting  those  avenues  which  are  used  by  carriages  of 
luxury.  This,  however,  was  not  fully  carried  out. 

Many  adverse  criticisms  are  made  on  Macadam  roads  by  parties  who 
judge  of  their  value  mainly  from  reading  statements  regarding  European 
Macadam.  A  well-made  trap  road,  when  properly  watered  and  main- 
tained, is,  after  an  earth  road,  the  pleasantest  and  safest  road  known.  In 
this  locality  a  road  15  feet  wide  would  give  suburban  residents  the  same 
easy  access  to  their  railroad  stations  in  the  worst  winter  weather  as  in 
summer.  And  for  streets  of  residence,  \\here  the  inhabitants  would  keep 
them  free  from  garbage,  both  for  quiet,  safety  to  horses,  and  on  sanitary 
grounds,  they  are  preferable  to  the  ordinary  paving. 

It  is  possible  that  with  thoroughly  compacted  and  bound  roads,  the 
English  and  French  engineers  would  look  with  more  favor  on  Telford 
foundations,  for  with  the  roads  we  make,  the  wear  between  the  Macadam 
and  Telford  must  be  very  slight,  the  pressure  of  a  wheel  being  spread 
over  a  large  surface.  They  are  preferred  here  because  they  give  an  equa 
depth  of  foundation  more  cheaply  than  with  broken  stone,  and  as  in  this 
country  municipal  appointments  of  engineers  are  sometimes  influenced 
by  political  considerations,  the  general  desire  is  to  build  as  solidly  as  pos- 
sible. 

One  objection  that  may  be  urged  against  the  Telford  foundation  is  the 
fact  that  it  does  not  have  a  solid  bearing  on  the  earth  roadbed,  and  when 
the  road  is  worn  thin  the  spaces  between  the  stones  may  become  filled 
with  water  and  mud,  which  will  work  through  the  foundation  into  the 
broken  stone,  hurrying  the  disintegration  of  the  road. 

The  English  engineers  often  use  "hard  core,"  a  mixture  of  brick 
rubbish,  old  plastering  and  broken  stone,  on  a  clay  soil,  to  prevent  the  mud 
working  into  the  metaling. 

The  result  was  accomplished  by  the  use  of  six  to  eight  inches  of  fine 
sand  on  Mott  avenue,  New  York,  which  was  built  at  the  joint  expense  of 
the  city  and  private  parties.  The  regulation  of  the  surface  required  a 
maximum  cut  of  two  and  a  half  feet  and  a  fill  of  four  feet ;  the  soil  was  a 
heavy  loam,  thoroughly  saturated  by  the  fall  rains,  which  continued  until 
the  work  was  completed,  and  it  was  desirable  to  Macadamize  it  immedi- 
ately. Rough  gneiss  rock  was  placed  on  the  layer  of  sand  and  rolled  to  an 
even  surface,  with  a  thickness  of  about  eight  inches,  and  on  thet  a  scant 
six  inches  of  loose  2-inch  trap,  to  which  thirty  per  cent,  of  screenings  were 
added.  The  bottom  was  very  treacherous  ;  on  about  half  the  road  it  was 
not  safe  to  stop  the  roller,  which  broke  through  in  two  instances  in  spite 
of  the  care  exercised.  Nor  could  the  road  be  rolled  long  in  one  place  ;  but 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    79 


as  soon  as  the  surface  began  to  weave  in  front  of  the  roller  it  was  given  a 
rest,  and  the  roller  taken  to  another  part  of  the  road.  In  spite  of  this  the 
road  was  compacted  and  the  surface  puddled  satisfactorily,  except  in  one 
or  two  small  patches.  It  has  stood  the  freezing  and  thawing  of  two  winters 
without  receiving  or  requiring  any  attention. 

It  is  held  that  the  success  of  this  operation,  so  contrary  to  the  teachings 
of  the  books,  was  due  to  the  layer  of  fine  sand  being  impervious  to  the 
mud,  which  without  it  would  have  been  over  the  top  of  the  Macadam  a 
long  time  before  it  was  puddled. 

The  deductions  of  the  French  engineers  from  the  table  cited  on  page 
12  should  have  been  strengthened  or  modified  by  a  statement  of  the  wear 
of  the  different  work  done.  And  their  principles  of  road  construction  are 
dissented  from,  because  the  writer  believes  that  the  horse-roller  made  road 
does  not  differ  so  much  (after  both  are  compacted)  in  wearing  value  from 
the  road  specified  by  Macadam  as  it  does  from  the  road  properly  made  by 
a  steam  roller;  that  all  binding  should  be  fully  as  hard  as  the  stone,  and 
that  the  better  road  is  made  with  the  heavier  roller  per  inch  run,  as  far  as 
his  experience  has  gone,  /.  e.,  up  to  460  pounds.  And,  in  addition,  up  to 
that  weight  the  ton  miles  rather  than  the  load  should  be  altered  on  ac- 
count of  the  greater  or  less  hardness  of  the  rock  employed  for  road  con- 
struction. 

It  is  believed  that  no  one  who  has  used  the  two  styles  of  2-ton  rollers 
mentioned,  viz.,  3  feet  and  6  feet  long,  doubts  that  the  3-foot  roller  will  do 
better  work  than  can  be  accomplished  by  the  6-foot  roller  without  leading. 

Under  the  writer's  direction  the  same  quality  of  syenitic  gneiss  men- 
tioned on  page  9  was  rolled  with  a  1 5-ton  steam  roller,  with  binding  of  the 
same  quality  in  both  cases.  There  were  only  about  200  cubic  yards  of  it, 
and  on  account  of  the  traffic  passing,  it  was  impossible  to  keep  an  exact 
account  of  the  work  done,  but  the  road  is  very  satisfactory,  and  from  it 
the  writer  thinks  that  a  few  passages  of  the  steam  roller  over  the  horse- 
rolled  road  would  .add  materially  to  its  life,  besides  greatly  reducing  the 
number  of  loose  stones  on  its  surface. 

Some  refuse  Westchester  marble  (a  very  soft  rock)  was  delivered  on 
some  of  the  roads  at  about  25  cents  per  cubic  yard,  and  hand  broken  in 
place  at  the  rate  of  about  i  cubic  yard  per  hour.  A  portion  was  rolled 
before  any  traffic  went  over  it,  some  after  about  two  weeks  of  traffic  and 
some  after  six  weeks  ;  of  the  rest,  part  was  horse  rolled  and  part  com- 
pacted by  wheels  ;  the  quality  of  the  stone,  traffic,  etc.,  were  very  nearly 
the  same ;  that  not  rolled  by  the  steam  roller  soon  wore  into  holes;  the 
first  mentioned  is,  after  standing  two  winters,  in  very  fair  surface ;  the 
others  decreasing  in  the  order  in  which  they  are  mentioned.  This  dif- 
ference is  so  noticeable  that  any  one  could  pick  out  their  sequence  as  men- 
tioned. 


8o     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 


Shortly  before  this,  however,  the  writer  very  nearly  made  a  mush  of 
some  micaceous  gneiss  in  trying  to  reduce  the  crown  of  a  road  covered 
with  it. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    81 

Late  in  the  fall  a  portion  of  the  Southern  Boulevard  was  repaired  with 
2-inch  trap,  screenings,  and  a  2-ton  horse  roller.  After  the  metal  was 
compacted  a  thin  coat  of  clay  hard-pan  was  added,  which  froze  solidly 
that  night,  and  a  day  or  two  after  was  covered  with  snow  which  stayed  on 
till  spring,  thus  giving  it  the  most  favorable  surroundings  possible.  In  the 
summer  there  was  but  little  difference  between  it  and  the  steam  rolled 
part ;  but  by  fall  it  had  commenced  to  deteriorate,  and  now  its  surface  is 
but  little  better  than  that  made  seven  years  before. 

Both  the  English  and  French  prefer  hand-broken  stones  for  Macadam. 
An  experienced  breaker  will  make  better  shaped  stones  than  any  crusher 
can,  and  hand-breaking  would  afford  employment  to  labor.  The  hand- 
broken  stones  mentioned  above  were  delivered  by  contractors  at  $2.00  per 
cubic  yard ;  the  men  who  broke  receiving  on  an  average  82 >£  cents  per 
yard.  One  man  was  thought  to  have  broken  at  the  rate  of  4.5  cubic  yards 
per  day;  about  6  to  average  2>£  yards  or  more.  They  stood,  using 
hammers  weighing  i  ^  to  2  pounds,  on  very  flexible  handles.  The  ave- 
rage of  all  who  worked  could  not  have  been  much  over  i  yard  per  day. 

On  the  other  hand,  there  is  not  enough  fine  stone  for  binding,  what 
there  is  is  full  of  dirt,  and  machine  breaking  is  cheaper  ;  the  cost  of  crush- 
ing trap  with  a  Blake  crusher,  after  it  is  sledged,  being  understood  to  be 
less  than  70  cents. 

The  crown  or  transverse  section  of  a  road  should  depend  on  so  many 
different  considerations  that  no  general  rule  can  be  drawn  for  it.  With 
Macadam  made  from  hard  material,  the  less  crown,  on  many  accounts, 
the  better,  as  the  surface  is  benefited  by  being  kept  damp.  In  narrow 
wheelways,  particularly,  an  excessive  crown  throws  all  the  traffic,  as  much 
as  possible,  in  one  line,  whatever  the  material  may  be.  On  the  other 
hand,  in  curbed  streets,  if  the  road  is  too  flat,  the  heavy  traffic  tends  10 
concentrate  near  the  gutters.  The  crowns  given  to  dirt  roads  are  in- 
tended to  drain  off  the  water,  but  the  longitudinal  ruts  soon  defeat  that 
object. 

Transverse  profiles  of  the  Western  Boulevard  and  Sixth  Avenue,  New 
York  City,  are  shown  on  page  80.  On  the  former,  though  the  transverse 
slope  is  so  slight,  it  is  perceptible  to  a  person  riding  in  a  vehicle  with  longi- 
tudinal seats,  but  is  not  noticeable  when  on  a  transverse  seat.  The  cross 
section  of  Sixth  Avenue  shows  the  surface  as  the  road  was  constructed  by 
M.  A.  Kellogg,  Engineer,  in  1872  and  1873,  with  the  crown  at  the  same 
height  as  the  top  of  the  curb  stones,  and  the  figures  above  the  dotted  line 
joining  the  curbs  show  the  average  distance  of  the  surface  below  street 
line,  as  found  by  careful  levels  taken  this  spring  between  I2$d  and  I24th 
streets,  a  point  where  no  broken  stone  had  been  added,  the  wear  at  the 
crown  being  o.i  5  foot,  or  about  j^-inch  per  year.  The  road  is  not  too 
flat,  as  it  now  stands,  to  shed  the  rainfall. 


82     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

The  amount  of  water  the  writer  found  necessary  to  keep  earth  or  Mac- 
adam roads  from  becoming  dusty,  was,  for  a  well  maintained  earth  road, 
at  the  rate  of  71.3  cubic  feet  per  1,000  square  yards,  applied  twice  in  a 
day,  or  say  143  cubic  feet  per  day.  In  very  hot  or  breezy  weather  this  was 
not  quite  enough. 

On  the  Telford  roads  of  this  city,  25  cubic  feet,  applied  four  times  a 
day,  are  necessary  per  1,000  square  yards,  say  100  cubic  feet  per  day. 
One  water  cart,  holding  79  cubic  feet,  waters  35,000  square  yards  four 
times  a  day,  keeping  it  free  from  dust,  except  during  windy  weather. 

In  Paris  about  27  per  cent,  of  the  surface  is  watered  by  hand  hose. 
These  are  made  of  iron  pipes  about  6>£  feet  long,  each  end  supported  on 
castors  and  connected  with  leather  or  rubber  couplings ;  the  working  end 
being  a  piece  of  rubber  hose.  Its  cost  is  one-half  that  of  watering  by  carts 
holding  46  cubic  feet. 

STONE  PAVEMENTS. 

The  City  of  New  York  is  largely  paved  with  the  Belgian  pavement,  i.e., 
truncated  pyramids  of  trap  set  in  coarse  sand.  The  sand  soon  becomes 
saturated  with  the  water  and  mud  of  the  streets,  and  the  blocks  working 
under  the  traffic  become  rounded.  It  is  impossible  to  keep  such  pave- 
ments in  fair  surface,  and  they  are  as  bad  sanitarily  as  pavements  can  be. 

The  pavements  now  laid  are  of  granite  or  trap  blocks,  4  inches  wide,  6 
inches  deep,  and  8  to  12  inches  long.  They  have  parallel  sides,  and  are 
laid  in  sand,  probably  forming  the  most  efficient  pavement  ($1.91  per 
square  yard),  to  be  found  anywhere.  The  open  joints  filled  only  with  sand 
are  objectionable,  however,  as  forming  receptacles  for  street  mud  and 
water. 

The  Guidet  pavement  laid  in  Broadway,  with  a  foundation  of  concrete, 
has  lasted  very  well,  its  increased  wear  probably  compensating  for  the  ad- 
ditional cost  of  the  concrete  foundation. 

In  Paris,  the  new  pavements  are  of  Gris,  a  hard  sandstone,  which  is 
neatly  dressed  in  blocks,  4  to  5  inches  square,  and  laid  either  in  sand  or 
mortar,  and  porphry,  about  4  inches  wide,  6  inches  deep,  and  8  inches  long, 
generally  laid  in  mortar. 

The  best  granite  pavements  are  found  in  England.  In  London,  where 
the  soil  is  clay,  the  usual  practice  is  to  lay  a  foundation  course  of  "  hard 
core  "  which  is  well  compacted  by  rolling,  &c.,  and  the  stones  are  set  on 
this  in  two  inches  cf  sand.  The  better  class  of  pavements,  on  clay,  have  3 
to  6  inches  of  hard  core,  9  inches  of  concrete,  and  two  inches  of  sand.  Col. 
Haywood,  where  soil  is  sand  or  gravel,  puts  down  9  to  18  inches  of  broken 
stone,  or  9  inches  of  concrete,  saying  that  there  is  little  difference  in  the 
stability  of  the  two  foundations,  but  the  concrete  is  apt  to  be  replaced  in  a 
more  satisfactory  condition  when  the  street  has  been  opened. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    83 

In  all  the  better  class  of  London  pavements,  the  sets  are  3  inches  wide, 
neatly  split  out  with  parallel  sides,  and  set  in  blue  lias  lime  grout,  Aber- 
deen granite  being  chosen  in  preference  to  harder  varieties,  as  it  wears 
rough.  Though  Col.  Hay  wood  determined  that  the  duration  of  the  same 
stone  varied  directly  with  their  size,  these  narrow  sets  are  preferred,  as 
making  a  smoother  road,  affording  a  better  foothold  for  horses,  and  in- 
creasing the  quietness  and  general  comfort.  The  practice  is  to  take  up  the 
sets  when  their  surfaces  become  rounded,  and  redress  them,  after  which 
they  are  relaid  in  streets  of  secondary  traffic.  The  spalls  are  useful  for- 
foundations  and  Macadam.  Col.  Haywood  estimates  the  total  life  of  such 
paving  stones  to  be  29  years. 

In  Liverpool,  Geo.  F.  Deacon  prefers  the  Welch  traps  and  granites, 
which  are  rather  harder  than  our  trap.  The  pavement  of  North  John 
Street,  which  has  a  traffic  of  4,000  vehicles,  averaging 3  tons  each,  per  day, 
is  of  trap  blocks,  neatly  split  out,  with  parallel  sides,  6  inches  deep,  and3# 
X3X  inches  on  the  face,  set  on  10  inches  of  concrete;  the  joints  are  filled 
with  gravel,  about  the  size  of  a  pea,  free  from  sand,  and  then  run  with  coat 
tar  pitch.  It  had  been  paved  very  close,  and  the  sets  were  so  firmly  held 
in  place  that  there  was  hardly  any  rounding  of  the  surface  last  winter, 
though  it  was  laid  in  1872.  The  surface  was  admirable,  and  showed  very 
slight  wear,  and  on  sanitary  grounds  it  is  probably  unequaled  by  any 
other  pavement,  except  compressed  asphalte,  for  there  can  be  no  percola- 
tion of  the  surface  water.  The  only  signs  of  failure  shown  by  this  pave- 
ment is  where  the  boiler  of  the  "  Montana,"  weighing  with  its  4-wheeled 
truck  59  tons,  passed  over  it,  crushing  some  of  the  sets,  and  showing  that 
stones  3^  inches  square  on  the  face,  are  not  large  enough  to  stand  loads 
of  15  tons  per  wheel. 

Mr.  Deacon  thinks  that  the  3^  inch  square  blocks  present  too  many 
longitudinal  joints,  and  now  employs  sets  3  inches  thick  by  6%  inches 
deep,  and  5  to  7  inches  long ;  the  specification  for  thickness  is  that  any  4 
of  them,  when  set  side  by  side,  shall  measure  12  inches,  and  not  more  than 
14  inches.  It  is  said  the  specification  is  filled  without  extra  cost. 

WOOD  PAVEMENTS. 

In  London,  the  principal  wood  pavements  are  Gary's,  the  improved 
Wood,  Henson's,  and  the  Asphaltic  Wood.  Gary's  is  laid  on  sand  or 
gravel,  a  firm  foundation  being  first  made.  The  patent  is  for  dovetailing 
the  blocks  on  their  ends,  which  is  held  by  the  inventor  to  give  the  pave- 
ment greater  stability.  The  joints  are  flushed  with  blue  lias  lime  grout. 
The  advantage  claimed  for  this  pavement  is  the  ease  with  which  it  can  be 
repaired,  the  method  being  apparently  to  take  out  the  defective  block  or 
blocks,  cut  off  the  broomed  portion  that  overhangs  the  sides  of  the  blocks, 
put  in  enough  gravel  to  restore  the  surface,  replace  the  block  with  the 


84    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

other  face  up,  and  run  in  the  grout.  A  portion  of  Cannon  street  is  laid 
with  this  pavement.  It  is  said  by  persons  on  the  street  to  require  fre- 
quent repairs.  Its  power  of  resisting  wear  must  depend  on  its  founda- 
tion, and  it  can  hardly  prevent  water  from  working  into  and  through  the 
foundation. 

The  "  Improved  Wood"  Company  started  to  make  an  improvement  on 
the  Nicholson  patent,  using  two  tarred  boards,  resting  on  sand,  under  the 
blocks.  Ludgate  Hill,  and  some  other  streets,  were  laid  on  this  principle, 
but,  under  the  heavy  traffic,  the  two  boards  acted  like  a  pump,  pumping 
the  sand  up  through  the  pavement.  After  trying  and  discarding  one 
board  laid  on  concrete,  they  now  lay  a  foundation  of  concrete  6  inches 
thick,  on  which  the  blocks  are  placed  ;  the  joints  are  filled  with  pitch  and 
gravel.  This  modification  apparently  makes  a  good  pavement,  as  seen  on 
Ludgate  Hill,  where  the  first  pavement  has  been  renewed,  and  at  St. 
Paul's  Church-yard.  No  company  now  lays  boards  as  a  part  of  its  founda- 
tion. 

Under  the  name  of  Ligneo  Mineral  Pavement,  a  company  laid  some 
pavement  of  hard  wood,  but  it  proved  so  slippery  that  work  under  that 
patent  has  been  mostly  abandoned.  The  most  work  seems  to  be  done,  at 
present,  by  the  Henson  and  Asphaltic  Wood  companies. 

In  the  Henson  pavement  the  6  inches  of  concrete  is  covered  with  a 
layer  of  tarred  felt  paper,  on  which  the  blocks  rest,  while  a  strip  of  the 
same  material  is  placed  vertically  between  each  row  of  blocks  across  the 
street.  Nothing  is  interposed  between  the  ends  of  the  blocks.  After  each 
few  courses  are  laid  the  blocks  are  driven  close  together  by  a  heavy  maul. 
Hot  coal  tar  and  pitch  is  plentifully  applied  to  the  upper  surface,  after 
which  gravel  is  strewn  over  it.  It  will  be  observed  that  this  pavement  pre- 
sents about  as  small  a  joint  for  foothold  as  is  possible,  and  to  meet  objec- 
tions on  this  score,  at  first  about  every  fifth  course  had  a  V-shaped  groove 
cut  in  its  top.  This  has  been  abandoned  by  the  company,  who  now  lay 
the  surface  flush,  making  a  road  almost  free  from  noise  and  near- 
ly as  smooth  as  a  compressed  asphalte  pavement.  In  answer  to  objec- 
tions to  their  narrow  joints,  their  engineer  asserted  that  they  had 
changed  the  practice  of  the  other  companies  in  London  from  i#  or  i  inch 
joints  to  as  near  a  quarter  of  an  inch  as  it  is  practicable  to  make  them,  to 
the  decided  advantage  of  all  pavements.  They  also  assert  that  the  tarred 
felt  under  the  blocks  will  not  wear  out,  that  the  pavement  is  impermeable 
to  water,  and  that  it  can  be  more  thoroughly  cleaned  than  any  other  wood 
pavement.  This  pavement  was  taken  up,  for  pipe  connections,  in  Leaden- 
hall  Street  and  High  Holborn.  Although  it  had  been  raining  in  the  first 
instance,  and  raining  and  freezing  in  the  other,  the  wood  was  bright  and 
not  at  all  watersoaked ;  the  felt  underneath,  however,  was  considerably 
worn.  The  claim  in  regard  to  cleaning  is  probably  correct. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    85 


The  asphaltic  wood  pavement,  laid  under  the  patent  of  H.  S.  Copland, 
C.  E.,  has  on  the  6  inches  of  concrete  a  quarter  of  an  inch  of  tempered 
Trinidad  bitumen,  on  which  the  blocks  are  placed  ;  the  joints  across  the 
street,  which  are  kept  between  a  quarter  and  an  eighth  of  an  inch,  are  run 
with  a  softer  bitumen  for  about  2  inches,  and  flushed  with  lias  lime  grout, 
the  ends  of  the  blocks  abutting  against  each  other  ;  the  whole  is  covered 
with  gravel.  The  pavement,  unless  cracked  by  the  settlement  of  the 
foundation,  must  be  as  impervious  to  water  as  one  of  asphalte,  and  should 
stand  the  traffic  very  well.  On  account  of  its  rigid  foundation  it  is  more 
noisy  than  the  Henson,  and  having  a  slightly  wider  transverse  joint,  it 
hardly  rides  as  smoothly  after  some  wear,  though  the  difference  would  not 
be  readily  noticed.  It  should  be  noticed  that  the  bitumen  which  is  run  in 
the  joints  makes  a  firm  bond  with  the  layer  under  the  blocks,  and  more 
wood  is  spoiled  in  taking  up  this  pavement  than  any  other  observed. 

This  pavement  was  first  laid  in  Cannon  street,  between  Abchurch  and 
Laurence  Pountney  Lanes,  in  July,  1874.  It  was  laid,  apparently,  with 
joints  rather  over  than  under  I  inch,  and  in  December,  1878,  the  edges  of 
each  block  had  broomed  over  into  the  joint ;  otherwise  the  surface  was 
good,  and  I  could  not  learn  from  any  source  that  repairs  had  been  made 
on  it,  except  when  the  street  had  been  opened  for  pipes.  The  grade  is  I 
in  90 ;  and  in  1873  the  number  of  horses  passing  over  it  in  12  hours — from 
8  A.  M.  to  8  P.  M.— was  5,350. 

The  practice  in  London  is  to  cover  the  surface  of  wood  pavements 
several  times  a  year  with  hard  gravel,  which  is  beaten  into  the  ends  of  the 
fibres  by  the  traffic,  tending  to  preserve  the  blocks  from  wear  and,  it  is 
claimed,  from  decay.  The  wood  used  is  a  species  of  pine — Baltic  fir — harder 
than  our  white  pine  and  softer  than  Southern  or  pitch  pine,  resembling 
what  is  sold  in  the  Chicago  markets  as  Norway  pine  ;  it  is  better  seasoned 
than  the  pine  generally  used  by  house  carpenters  in  this  country,  and  it  is 
usually  laid  without  being  creosoted,  the  borough  surveyors  claiming  that 
the  difficulties  of  inspection  are  increased  by  creosoting ;  but  as  far  as 
noticed,  for  renewals  and  repairs,  which  are  made  by  the  companies  under 
their  contracts  for  maintenance,  creosoted  wood  is  used,  their  managers 
saying  that  they  expect  it  to  add  to  the  wearing  qualities  of  the  wood  as 
well  as  to  protect  it  from  decay.  The  concrete,  usually  covered  with  a 
thin  coating  of  cement  mortar,  is  made  of  one  part  of  Portland  cement  to 
six  parts  of  Thames  ballast,  which  varies  in  size,  from  sand  to  pebbles 
three-quarters  of  an  inch  in  diameter. 

It  is  rather  difficult  to  arrive  at  the  durability  of  either  wood  or  asphalte 
pavements  in  London,  as  Col.  Haywood,  the  City  Engineer,  lets  them  at 
a  certain  price,  with  a  provision  that  they  shall  be  kept  in  repair  for  a  term 
of  years  at  a  certain  price  per  square  yard  per  annum,  a  good  pavement 
being  turned  over  to  the  city  at  the  expiration  of  the  contract  for  main- 


86    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

tenance,  the  contractor,  in  the  meantime,  replacing  the  entire  roadway,  if 
necessary,  as  will  be  noticed  under  the  head  of  asphalte.  This  plan  has 
worked  so  well  in  the  city  that  the  surveyors  for  the  vestries  have  gener- 
ally adopted  it,  so  that,  in  London,  the  wood  paving  contracts  are  usually 
let  with  the  same  length  of  maintenance  as  for  compressed  asphalte,  and 
at  about  the  same  price,  viz.,  at  a  first  cost  of  from  $4.38  to  $3.90  per 
square  yard,  including  foundation,  but  not  excavation.  They  are  kept  in 
repair  for  two  years  at  the  contractor's  cost,  and  at  the  rate,  depending  on 
*he  amount  of  traffic,  of  from  36^  to  i8X  cents  per  square  yard  per 
annum  for  the  succeeding  fifteen  years. 

From  the  report  of  Col.  Havwood  to  the  Commissioners  of  Sewers  of 
the  City  of  London  upon  asphalte  and  wood  pavements,  1874,  page  38, 
et  seg.,  we  find  that  the  greatest  duration  of  any  wood  pavement  was  in 
Mincing  Lane,  nineteen  years  and  one  month  ;  the  average  cost  per  square 
yard  per  annum  having  been,  in  that  instance,  thirty-five  and  one-half 
cents,  while  the  average  cost  of  three  heavy  traffic  streets  had  been  sixty- 
three  and  nine-tenths  cents.  He  concludes  that,  with  necessary  repairs 
wood  pavements  will  last  ten  years  in  London. 

Law  &  Clark's  Roads  and  Streets,  page  239,  gives  the  wear  of  three 
wood  pavements  at  three-tenths  of  an  inch  per  annum  under  a  traffic 
averaging  362  vehicles  per  day  of  twelve  hours  for  each  foot  in  width  of 
the  street.  Mr.  Clark  says  it  is  claimed,  in  some  instances,  blocks  have 
worn  down  in  London  to  a  depth  of  two  and  one-half  inches  (the  Wells 
street  pavement  was  only  two  inches  thick,  before  removal),  and  suggests 
eight  or  nine  inches  as  a  better  depth  than  six  inches,  now  universal. 
The  blocks  of  the  Mincing  Lane  pavement,  which  lasted  nineteen  years, 
were  nine  inches  deep.  If  we  assume  that  the  blocks  are  six  inches  deep, 
and  that  the  road  will  not  break  up  until  they  have  worn  down  three  inches, 
there  seems  no  reason  why  a  thoroughly  creosoted  wood  pavement,  laid 
with  narrow  joints,  on  a  sufficient  bed  of  concrete,  wkh  a  water-tight 
stratum  interposed,  should  not  wear  for  about  ten  years  in  our  streets  of 
heaviest  traffic  with  a  small  amount  of  intelligent  maintenance. 

There  have  been  several  charges  made  against  wood  pavements,  which 
are  mentioned  here,  not  as  a  matter  of  information,  viz.,  that  they  soon 
become  full  of  holes,  are  impossible  to  clean,  are  difficult  to  replace  when 
the  street  is  opened,  and  that  by  their  rotting  the  health  of  the  community 
is  endangered,  to  which  may  be  added  that  for  only  a  short  time  do  they 
present  any  barrier  to  the  saturation  of  the  soil  by  surface  water. 

The  general  practice,  as  far  as  observed  by  the  writer,  in  this  country 
has  been  to  lay  green  or  wet  pine  blocks,  more  or  less  thoroughly  dipped 
in  coal  tar,  on  a  bed  of  sand,  not  always  thoroughly  rammed,  with  or 
without  the  interposition  of  a  tarred  pine  board,  with  transverse  joints 
from  one  to  one  and  one-half  inches  wide  filled  with  gravel  and  coal 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    87 

tar,  which  was  theoretically  thoroughly  compacted.  Omitting  those 
which,  without  the  slight  pretense  of  a  i-inch  board  for  foundation, 
speedily  become  a  wood  Macadam,  the  first  failure  was  from  the 
blocks  rotting  on  the  bottom  in  patches,  so  that  the  surface  would 
first  be  found  to  be  sheared  down  by  a  heavy  load ;  and  on  taking  out 
the  blocks  they  would  be  found  sound  on  their  tops,  where  the  gravel 
had  been  driven  into  them  by  the  traffic,  and  also  a  sound  film  of  about 
the  thickness  that  tar  could  be  expected  to  penetrate  a  wet  block,  the 
inside  being  rotten.  In  other  cases,  however,  when  the  layer  of  sand 
was  too  thin,  the  mud  worked  up  through  both  boards  and  blocks, 
reducing  everything  to  about  the  state  of  those  having  no  boards  under 
them. 

A  layer  of  concrete,  covered  with  Trinidad  bitumen,  will  effectually 
stop  the  mud  from  coming  up,  and  any  percolation  of  the  surface  water 
into  the  soil  through  the  pavement ;  the  narrow  joints,  by  preventing  the 
edges  of  the  blocks  burring  over,  will  both  tend  to  keep  the  surface 
smooth,  lessening  the  shocks  of  the  wheels,  and  greatly  facilitate  all  the 
operations  of  cleansing.  Creosoting,  by  the  preservative  and  antiseptic 
properties  of  the  dead  oils  used  in  that  process,  will  probably  keep  the 
timber  from  decay,  so  that  nothing  but  abrasion  need  be  feared,  and  the 
sanitary  objections  to  decaying  wood  will  be  removed. 

The  following  note  of  some  experiments  by  E.  R.  ANDREWS  (pub- 
lished in  "  Engineering  News  ")  shows  the  efficacy  of  creosoting  for  pro- 
tecting wood  from  moisture. 

The  following  are  the  results  of  some  careful  experiments  with  differ- 
ent varieties  of  wood,  half  of  the  specimens  being  simply  dried  and  the 
others  creosoted,  to  ascertain  to  what  extent  wood  is  rendered  water-proof 
by  creosoting.  The  specimens  were  soaked  during  two  days  in  water,  be- 
ing carefully  weighed  before  and  after  soaking  : 

Percentage  of 
water  absorbed. 
Spruce,  creosoted 0286 


"      dried  only 1754 

3333 

"      Burnettized 2500 

Hard  piue,  creosottd 0000 

"  dried  only 1600 

Oak,  creosoted 0625 

"      dried  only 2000 

White  birch,  creosoted .' .     .1240 

dried  only 4300 

Cotton  wood,  creosoted     3470 

dried  only 7140 

Black  gum,  creosoted 1250 

dried  only 1.0000 

Sesquoia  Gigantea  (great  tree  of  California),  creosoted   0000 

dried  only. 4722 

In  the  rooms  of  this  Society  are  creosoted  fir  ties  from  England  that 
have  been  in  the  track  for  20  years,  and  apparently  justify  the  assertion  of 
the  engineer  sending  them,  that  they  are  good  for  10  years  more. 


88     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

The  following  extract,  from  the  "  Railroad  Gazette,"  is  also  corrob- 
orative : 

The  German  Railroad  Union  some  time  ago  made  inquiries  as  to  the 
extent  to  which  processes  for  preserving  ties  were  employed,  and  what  the 
results  were. 

It  appears  from  statistics  of  German  railroads  which  have  used  treated 
ties  more  or  less  since  1840,  and  therefore  have  had  time  to  test  thorough- 
ly the  life  of  the  ties,  that  the  average  life  of  ties  not  treated,  and  of  those 
treated  with  chloride  of  zinc  or  creosote  has  been  : 

Not  treated.  Treated. 

Oak  ties 13.6  years.  19.5  years. 

Fir  ties 7.2      •'  14  to  16        " 

Pine  ties  5.0     "  8  to  10        " 

Beechties 3.0     "  15  to  18        " 

The  average  life  of  831,341  pine  ties  treated  in  various  ways  on  thirteen. 
German  roads  was  14  years. 

It  follows  from  this  that  there  is  an  increase  in  the  life  of  ties  treated 
with  chloride  of  zinc  or  creosote,  amounting  to  about  40  per  cent,  for  oak, 
ico  to  130  per  cent,  for  fir,  60  to  100  per  cent,  for  pine,  and  400  to  500  per 
cent,  for  beech. 

It  thus  appears  that  there  is  a  great  deal  gained  with  any  kind  of 
wood,  but  most  with  some  of  those  usually  not  considered  good  for 
ties,  fir  and  beech  being  made  almost  as  durable  as  oak.  Bischoff  savs 
that  it  is  of  little  advantage  to  secure  the  ties  from  decay  for  longer  periods 
than  above  stated,  as  the  ties  usually  become  worn  out  or  crushed  by  that 
time,  even  if  not  decayed. 

Commenting  on  these  facts,  Bischoff  says  that  it  is  now  generally  ad- 
mitted that  the  choice  lies  between  creosote  and  chloride  of  zinc ;  that 
creosote  is  the  best  antiseptic  material,  but  also  that  it  is  the  dearest. 

There  can  be  but  little  doubt  that  the  antiseptic  properties  of  the 
creosoting  process  are  of  more  value  than  the  increased  life  it  would  give 
to  the  blocks. 

On  account  of  the  absence  of  proper  stone  and  the  cheapness  of  wood 
in  large  areas  of  our  country,  the  small  first  cost  of  wood  pavements  seems. 
to  make  it  worth  while  to  give  them  an  intelligent  trial. 

The  thoroughness  with  which  wood  pavements  can  be  cleansed  de- 
pends on  the  size  of  the  joints  and  the  firmness  of  their  filling.  The 
practice  in  London,  when  the  mud  is  at  all  sticky  and  not  so  thick  as  to 
require  scraping,  is  to  water  and  then  sweep  with  a  revolving  broom,  the 
thoroughness  of  the  cleansing  being  almost  directly  as  the  amount  of 
water.  In  hot  weather  a  disinfectant  is  sometimes  applied  after  sweep- 
ing. 

ASPHALTE  AND    BITUMEN. 

Dictionary  and  encyclopedia  makers,  as  well  as  chemists,  seem  to  use 
these  terms  interchangeably.  M.  Leon  Mab,  in  his  "  Guide  Pratique 
pour  La  Fabrication  et  L' Application  de  L'Asphalte  et  des  Bitumes" 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.     89 

after  speaking  of  the  lack  of  definition  in  the  two  terms  as  generally  used, 
gives  the  following,  viz. : 

"  Asphalte,  Bituminous  Limestone." 

"Bitumen,  The  black  and  viscid  substance  which  we  find  disseminated 
in  the  pores  of  bituminous  limestone  and  in  the  interstices  of  the  molasses 
of  Seyssel  or  the  sands  of  Auvergne." 

"  Asphaltic  Mastic,  Bituminous  limestone  transformed  by  dressing 
(cuissori)  and  by  the  addition  of  a  small  quantity  of  bitumen." 

He  adds :  "  We  employ  these  definitions  throughout  this  work,  and 
give  to  them  the  senses  which  we  have  just  indicated,  and  I  hope  strong- 
ly that  they  will  be  adopted  for  use,  for  they  seem  to  be  the  most  reason- 
able.'' 

It  is  believed  his  definitions  have  been  generally  accepted  by  European 
technical  writers  and  in  specifications  relating  to  the  use  of  these  mate- 
rials,* and  the  writer  in  this  paper  will  use  them  as  above  defined,  except- 
ing that  the  bitumens  from  Trinidad  and  Cuba  will  be  included  with  those 
mentioned  by  M  Malo. 

In  view  of  the  practice  in  this  country  two  other  definitions  seem  neces- 
sary, viz.: 

Bituminous  mastics,  mixtures  of  bitumen,  either  having  an  earthy 
gangue,  hke  those  of  Trinidad  and  Cuba,  or  purer  ones,  like  Grahamite 
and  Albertite,  with  limestone  or  other  substances  not  naturally  impreg- 
nated, which  add  to  its  resistance  to  wear,  and — 

Tar  Mastic,  a  mixture  in  which  the  bitumen  is  replaced  by  (usually) 
gas  tar. 

M.  Malo  further  characterizes  asphalte  as  a  carbonate  of  lime  perfectly 
pure  (excepting,  sometimes,  a  trace  of  silica),  naturally  impregnated  with 
bitumen.  Its  characteristic  color  is  that  of  chocolate — which  it  also  resem- 
bles in  fracture— mean  specific  gra\ity  2.235.  It  *s  quite  hard  when  cold, 
and  falls  to  pieces  at  a  heat  of  about  122  deg.-i4o  deg.  F.  At  an  interme- 
diate temperature  it  flattens  under  the  blows  of  a  hammer  ;  its  structure 
varies  with  its  locality,  but  in  general  should  be  fine-grained  and  homoge- 
neous, without  particles  of  unimpregnated  stone. 

In  the  poorer  qualities  the  impregnation,  though  regular,  does  not  ex- 
ceed 6  per  cent.,  or  the  bitumen  is  injected  into  minute  cracks,  showing 
under  the  microscope  that  the  impregnation  is  not  molecular,  or  the  rock 
contains  clay,  or,  as  in  the  case  of  Lobsan,  the  bitumen  contains  light  oils 
which  injure  the  consistence  of  the  mastic,  in  which  case  the  light  oils  are 
driven  off  by  heat,  the  remainder  being  used. 

Generally,  we  may  say  that  the  more  uniform  and  microscopic  the 
impregnation  of  the  lime  is,  and  freer  from  extraneous  matters,  the  better 
it  is. 

*In  Paris,  the  asphalted  sidewalks  are  universally  spoken  of  as  bitumen,  in  distinction  from, 
wheelways,  which  are  called  asphalte. 


90    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

Neglecting  the  Tubal  Cain  stage  of  its  history,  asphalle  was  first  ap- 
plied to  sidewalks  and  wheelways  as  a  mastic,  but  in  that  state  was  not 
sufficiently  resistant  for  streets  of  much  traffic.  It  was  seen,  however, 
that  in  summer  the  pieces  of  rock  that  fell  from  the  carts  between  the 
mine  and  the  mastic  works  at  Seyssel  compressed  under  the  wheels.  In 
1849,  a  Swiss  Engineer,  M.  Merian,  put  this  lesson  to  profit,  by  construct- 
ing a  Macadam  road  of  asphalte,  which  was  compacted  with  a  roller.  In 
spite  of  the  instability  of  its  foundation  and  the  irregularity  of  its  mainte- 
nance, this  road  is  still  in  very  good  order.  (Malo,  p.  108.) 
COMPRESSED  ASPHALTE. 

The  first  compressed  asphalte  was  laid  in  Paris  by  M.  Vaudry  in  1854, 
though  it  was  not  till  1858  that  it  was  laid  on  a  large  scale ;  the  area 
covered  in  1878  by  pavements  and  cross-walks  was  324,654  square  yards, 
or  nearly  14  miles  of  a  street  with  a  4o-foot  wheelway.  The  earlier  prac- 
tice was  to  "  decrepitate  "  the  rock  (broken  to  abont  the  proper  size  for 
Macadam)  by  heating  it  to  about  140  degs.  F.  in  sha'low  iron  pans.  Skill 
was  necessary  in  this  operation,  as  the  rock  was  liable  to  be  burned,  /.  e.t 
have  too  much  of  the  bitumen  driven  off,  or  to  have  too  little,  and  some- 
times both  results  were  reached  in  the  same  batch.  The  walks  in  Union 
Square,  N.  Y.,  are  an  example  oi  the  ill  effects  of  unskillful  decrepitation. 

The  rock  was  also  broken  up  by  the  direct  action  of  steam,  but  it  was 
impossible  to  secure  a  product  of  uniform  fineness,  and  difficult  to  remove 
all  the  moisture.  After  experiments  with  various  machines,  a  Blake 
crusher  is  first  used,  the  pieces  are  then  passed  through  a  Carr's  disinte- 
grator, after  which  the  powdered  rock  is  heated  in  revolving  cylinders  to 
from  212  degs.  to  284  degs.  F.  (depending  partly  on  the  distance  it  has  to 
be  carried),  and  transported  to  the  place  where  it  is  to  be  laid,  usually  in 
covered  sheet-iron  wagons. 

The  permanence  of  this  pavement  depends  primarily  on  the  stability 
of  its  foundation,  which  is  usually  of  concrete  (though  old  asphalte  is 
sometimes  used)  6  inches  thick ;  on  this,  when  it  is  thoroughly  dried, 
the  heated  powder  is  spread,  by  means  of  rakes,  to  such  thickness  that 
when  compressed  it  shall  be  from  i>£  to  2>£  inches  thick— depending  on 
the  probable  amount  of  traffic.  The  compression,  which  is  termed  pilon- 
nage,  is  effected  by  the  aid  of  the  tools  figured.  The  fouloir  is  first  used 
along  the  junction  of  the  asphalte  with  either  the  curb-stone  or  the  paved 
gutters,  while  the  rest  of  the  surface  is  compacted  by  the  pilon,  beginning 
with  light  blows  and  ending  with  vigorous  ones.  All  these  tools  are 
heated  nearly  red  hot,  as  the  powder  sticks  to  them  when  they  are  cold. 
After  the  surface  has  been  thoroughly  compacted  it  is  tested  with  a 
straight-edge,  and  then  rubbed  with  the  lissoir,  also  heated,  giving  a  glaze 
to  the  surface,  after  which  it  is  dusted  over  with  cement  and  allowed  to 
cool  thoroughly  before  the  traffic  is  turned  on  it. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    91 

Efforts  have  been  made  to  secure  a  more  regular  surface  than  is  prac- 
ticable l>y  pilonnage  and  at  less  expense  by  rolling,  but  it  was  difficult  to 
so  heat  the  rollers  that  the  powder  would  not  adhere,  and  the  pavement 
was  liable  to  tear  as  it  was  about  finished. 

The  powder  retains  heat  for  some  time,  and  the  work  goes  on  in  a 
continuous  sheet  for  the  day,  a  gang  of  ten  or  twelve  men  being  able  to 
complete  about  600  square  yards  per  day.  In  the  morning  the  uncom- 
pressed powder  at  the  edge  of  the  work  of  the  day  before  is  swept  away, 
and  hot  powder  put  in  its  place,  which  in  turn  is  removed  after  having 
heated  the  old  work  ;  the  spreading  and  pilonnage  then  goes  on  as  before, 
leaving  small  or  no  trace  of  the  junction. 

Great  care  should  be  taken  that  the  concrete  foundation  is  thoroughly 
dry,  otherwise  the  hot  powder  evolves  steam,  which  permeates  the  powder 

Fouloir.  Pilon- 


and  leaves  the  compressed  mass  in  nodules  called  almonds.  These  do  not 
show  during  pilonnage,  but  are  developed  by  the  traffic,  when  the  place  is 
cut  out  and  refilled.  A  very  slight  defect  seems  capable  of  starting  a  hole 
in  compressed  asphalte,  and  for  the  first  two  weeks  it  is  under  traffic  it 
should  be  watched  closely  and  repaired  promptly.  The  defects  caused  by 
deficient  aggregation  of  the  molecules  show  themselves  more  readily  than 
those  caused  by  steam.  Overheating,  which  renders  the  asphalte  as  inert 
as  sand,  is  one  cause  of  deficient  aggregation,  and  laying  the  powder  too 
cold  is  another. 

When  the  asphalte  is  too  rich  in  bitumen  or  the  bitumen  is  too  oily, 
the  compressed  asphalte  forms  waves  under  the  traffic,  sometimes  longi- 
tudinal and  at  others  transverse. 

So  far  but  few  asphaltes  have  been  found  that  are  available  for  com- 
pressed pavements.  The  Val  de  Travers  (from  Neuchatel)  was  first  used, 


92     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

but  in  1867  Seyssel  (Pyrimont)  was  used  with  success  in  the  Rue  de 
Richelieu,  and  both  have  since  been  used  by  the  General  Asphalte  Com- 
pany of  Paris,  which,  until  January,  1878,  laid  and  maintained  the  asphalte 
roads  in  that  city.  The  Val  de  Travers  asphalte  is  of  the  two  more  reg- 
ular in  its  grain  and  impregnation,  and  richer  in  bitamen,  having  9  to  13 
per  cent.  Seyssel  is  not  so  regular  in  its  grain  and  impregnation,  and 
contains  from  7^  to  10  per  cent,  of  bitumen.  The  base  of  both  is  equally 
pure  carbonate  of  lime,  containing  about  2  per  cent,  as  a  maximum  of 
silica.  Of  the  two,  M.  Ernest  Chabrier,  for  a  long  time  manager  of  the 
Paris  Company,  in  his  paper  read  before  the  Institute  of  Civil  Engineers, 
says  :  "  No  engineer  could  conscientious^  say  that  the  Val  de  Travers  is 
better  than  the  Seyssel  asphalte.  The  former  may  be  safer  in  the  execu- 
tion of  a  work  not  subjected  to  supervision  ;  the  latter  offers  greater  guar- 
antees of  good  execution,  because  more  care  is  required  in  the  work." 

It  was  also  held  that,  for  compression  at  least,  the  two  should  not  be 
mixed,  and  that  only  pure  limestone,  impregnated  with  fr^m  8  to  12  per 
cent,  of  bitumen,  was  available  for  compression  ;  but  within  the  last  two 
or  three  years  the  Limmer  &  Vorwohle  Asphalte  Company  of  London 
found  their  mastic  pavement  breaking  up  and  employed  the  Sicilian 
arphalte  (which  is  certified  by  W.  J.  Fewtrell,  F.  R.  S.,  to  contain  as 
high  as  30  per  cent,  of  bitumen)  in  compressed  pavements  and  sidewalks. 
Aldgate  and  Newgate  streets  having  been  laid  with  this  asphalte  are 
apparently  wearing  well.  And  in  Paris,  Paul  Crochet,  who  has  the 
contract  for  new  work  and  maintenance  for  five  years  from  1878  (see 
Appendix,  No.  4)  has  used,  so  far,  a  mixture  of  Lobsan  and  Seyssel 
Forens-Nord.  M.  Malo  says  of  Lobsan  :  "  It  contains  within  its  bitumen 
an  oily  substance  which  renders  it  too  soft  and  injurious  to  the  consist- 
ence of  asphaltic  mastic;  we  free  it  from  this  oil  by  distillation,  after 
which  it  is  in  a  proper  state  to  be  used."  The  Seyssel  Forens  is  a  heavy 
limestone,  very  poor  in  bitumen.  As  after  a  careful  investigation  the 
engineers  of  the  Ponts  et  Chaussees  have  allowed  it  to  be  used  in  Paris 
it  seems  that,  theoretically,  at  least,  a  mixture  of  two  dissimilar  asphaltes 
is  not  disadvantageous,  nor  is  the  use  of  an  asphalte  that  contains  a  hydro- 
carbon of  the  more  volatile  series  ;  also  that,  as  in  the  case  of  the  Sicilian, 
an  asphalte  containing  more  than  twice  as  much  bitumen  as  was  formerly 
thought  the  safe  maximum  can  be  successfully  laid  under  exceptionally 
heavy  traffic. 

There  was  an  unwillingness  on  the  part  of  the  manager  of  the  Limmer 
&  Vorwohle  Company  to  explain  the  manner  in  which  he  handled  his 
material,  but  it  is  probable  that  it  was  skillfully  roasted  so  as  to  drive  off 
the  excess  of  bitumen  as  his  compressed  roadways  showed  less  tendency 
to  roll  in  hot  weather  than  those  laid  from  Val  de  Travers  rock. 

By  the  kindness  of  Count  Kielmansegge,  one  of  the  directors  of  the 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    93 

Neuchatel  Company,  I  am  able  to  give  the  following  analyses  of  Val  de 
Travers  asphalte.  These  two  sets  of  analyses  by  Charles  Heisch,  F.  C.  S., 
were  made  in  consequence  of  complaints  by  their  customers  that  the 
rock  was  becoming  too  rich  in  bitumen  : 

September,  1876.    5  samples. 

Bitumen...                            .     9.46  9.48  11.98  11.96  10.06 

Carbonate  of  lime 90.54  90.52  88.02  88.04  89.94 


100.00         100.00          100.00  100.00  100.00 

Loss  at  212°   1.46             1.42             3.04  8.22  1.92 

July,  18T7.    3  samples. 

Bitumen 10.2  11.5  12.32 

Carbonate  of  lime 89.8  88.5  t7.68 


100.0          100.0          100.00 
Lossat212° 2.46  2.6  8.2 

The  loss  was  moisture  and  light  oils.  A  small  amount  of  silica  was 
estimated  with  the  lime. 

Mr.  J.  Knight,  Secretary  Society  Francais  des  Asphaltes,  gave  me  the 
following  analyses  made  by  Steen,  of  Copenhagen  : 


Organic.  .   .  . 

12  00  -J  Soluble  ifi  ether.  . 

.    9.62 

Seyssel  Pyrimont  

|  Insoluble  in  ether 

.     2.85 

QA   An 

Seyssel  Garde  bois  

Inorganic  
Organic  

08-uul  Insoluble  in  acid. 
Q  nn/  Soluble  in  ether.. 
•     y'uu1  Insoluble  in  ether 

.     1.55 
.     9.15 
.       .55 

Inorganic.  .. 

on  qn/  Soluble  in  acid.  .  . 
au-du\  Insoluble  in  acid.  . 

.  85.10 
.     5.20 

The  Garde  bois  asphalte  is  only  used  as  a  mastic,  according  to  Mr. 
Knight,  not  having  coherence  enough  for  satisfactory  compression. 

Mr.  W.  H.  Delano,  manager  of  the  Compagnie  Generaledes  Asphaltes 
de  France,  says  of  an  asphalte  for  compression  that  "  it  should  be  carbon- 
ate of  lime  (without  admixture  of  foreign  material)  and  mineral  bitumen 
which  does  not  evaporate  at  302  degs.  F.  Some  bitumens  contain  an  oil 
which  commences  to  evaporate  at  158  degs.  F.;  they  may,  when  purged  of 
the  light  oil,  leave  an  excellent  quality  behind.  The  physical  qualities  of 
the  limestone  should  also  be  carefully  examined  ;  but  whatever  the  result 
of  even  a  careful  analysis  may  be,  the  value  of  a  new  asphalte  cannot  safe- 
ly be  determined  except  by  actual  experience  extending  over  three  years, 
at  least,  of  hard  winters  and  hot  summers."  Col.  Haywood  also  was  un- 
derstood to  say  that  at  least  three  years  were  necessary  to  prove  the  good 
qualities  of  a  new  or  untried  asphalte.  His  experience  is  strongly  against 
any  form  of  asphalte  pavement  except  "  compressed." 

From  a  sanitary  point  of  view  an  asphalte  pavement  is  without  a 
peer  ;  its  surface  is  smooth,  regular  and  non-absorbent,  with  no  cavities  or 
cracks  of  any  kind  to  retain  the  infected  mud  and  dust  of  the  streets,  and 
the  soil  beneath  it  is  kept  dry.  It  is  more  thoroughly  cleaned,  either  by 
sweeping  or  washing,  than  any  other  pavement.  Its  freedom  from  noise 
and  other  excellencies  is  fast  placing  it  in  all  the  business  and  banking 


94     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

streets  of  the  City  of  London,  where  it  seems  to  be  superseding  all  other 
pavements. 

In  comparison  with  granite  pavements,  its  great  economy  is  to  brain 
workers  and  the  owners  of  horses.  M.  Darcy  estimates  that  the  expense 
of  maintaining  and  renewing  horses  and  carriages  in  Paris  would  be  re- 
duced one-half  if  asphalte  was  substituted  for  pavement  throughout  the  city. 

Its  disadvantages  are,  it  is  expensive  ;  it  is  not  well  to  lay  it  on  a  grade 
much  greater  than  two  per  cent.;  it  is  subject  to  slight  decay  in  the  gut- 
ters, which  they  try  to  correct  in  Paris  by  laying  the  gutters  with  stone 
sets  ;  and  lastly,  the  most  serious  charge,  that  it  is  slippery  and  dangerous 
to  horses,  No  doubt  at  the  commencement  of  a  rain,  or  in  foggy  weather, 
its  surface  is  slippery  unless  it  is  very  clean,  and  a  horse  turned  suddenly 
is  liable  to  fall ;  but  when  dry  or  thoroughly  wet  no  such  charge  can  be 
brought  against  it. 

Referring  to  Col,  Haywood's  much  quoted  tables  comparing  granite, 
asphalte,  and  wood.we  find  that  before  an  accident  occurs  a  London  horse 
will  travel  on  granite  132,  on  asphalte  191,  and  on  wood  446  miles. 
"  That  of  those  accidents  which  are  most  obstructive  to  the  traffic,  as  well  as 
most  injurious  to  the  horses,  asphalte  had  the  greater  proportion,  granite 
the  next  and  wood  the  least." 

He  says  further  in  a  report  upon  asphalte  and  wood  pavements  : 

First. — As  regards  convenience :  That  asphalte  is  the  smoothest, 
driest,  cleanest,  most  pleasing  to  the  eye  and  the  most  agreeable  pave- 
ment for  general  purposes,  but  wood  is  the  most  quiet. 

Second. — As  regards  cleansing  :  That  wood  may  be  kept  cleaner  than 
it  hitherto  has  been,  but  will  be  more  difficult  to  cleanse  effectually  than 
asphalte.  That  as  both  pavements  require  occasionally  strewing  with 
sand  or  gravel,  there  is  no  difference  between  them  in  that  respect. 

Third. — As  regards  construction  and  repairs :  That  asphalte  and 
wood,  taking  all  seasons  into  account,  can  be  laid  and  repaired  with  about 
equal  facility  ;  but  the  smallest,  neatest,  cleanest  and  most  durable  repairs 
can  be  made  in  asphalte. 

Fourth. — As  regards  safety  :  That,  whether  considered  in  reference 
to  the  distance  that  a  horse  may  travel  before  it  meets  with  an  accident,  or 
the  nature  of  the  accident,  or  the  facility  with  which  a  horse  can  recover 
its  footing,  or  the  speed  at  which  it  is  safe  to  travel,  or  the  gradient  at 
which  the  material  can  be  laid,  wood  is  superior  to  asphalte. 

Fifth. — As  regards  durability  and  cost :  That  wood  pavements,  with 
repairs,  have,  in  this  city,  had  a  life  varying  from  six  to  nineteen  years, 
and  that,  with  repairs,  an  average  life  of  about  ten  years  may  be  obtained ; 
that  the  durability  of  the  asphaltes  is  not  known,  but  that  under  the  sys- 
tem of  maintenance  adopted  they  may  last  as  long  as  wood ;  that,  con- 
trasting the  tenders  for  laying  and  maintaining  for  a  term  of  years  the  two 
best  pavements  of  their  kinds,  wood  will  be  the  dearest. 

The  above  remarks  refer  to  London,  and  inasmuch  as  our  climate  is 
much  the  driest,  and  as  asphalte  is  safer  where  dry,  the  comparison  would  be 
more  in  favor  of  asphalte  here  than  there. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    95 

Both  the  compressed  and  mastic  surfaces  are  easily  and  thoroughly 
cleaned  by  washing  and  by  sweeping  when  either  wet  or  dry.  A  squeegee, 
which  is  a  long-handled  scraper  with  a  rubber  blade  32  inches  long,  when 
pushed  along  a  wet  pavement  both  cleans  and  dries  it. 

It  may  at  first  sight  seem  that  if  a  person  will  indulge  in  the  luxury 
of  changing  his  gas  company  on  the  recipt  of  each  bill  he  should  be  com- 
pelled to  make  good  the  surface  of  the  street,  and  the  ease  or  difficulty  of 
making  repairs  should  largely  be  a  consideration  for  those  who  open  the 
streets,  but  as  a  matter  of  fact  it  is  almost  impossible  to  properly  inspect 
the  work  of  plumbers,  and  while  one  avenue  in  this  city  has  on  its  surface 
a  double-tracked  horse  railroad  and  240  elevated  railroad  columns  per 
mile,  with  one  sewer,  three  water  pipes,  and  eight  gas  pipes  (belonging  to 
four  different  companies)  under  it,  the  subject  cannot  be  without  interest. 
In  general,  any  pavement  with  a  foundation  of  concrete  can  be,  and  prob- 
ably will  be,  more  thoroughly  repaired  than  one  with  a  loose  foundation, 
such  as  sand,  broken  stones,  or  Telford.  For  the  surface,  asphalte  is  su- 
perior to  all  others  in  the  matter  of  neatness,  Macadam  next,  and  tne 
granite  and  wood  pavements  next. 

ASPHALTIC  MASTIC. 

The  asphaltic  mastic,  which  is  greatly  used  in  Paris' for  sidewalks,  is> 
made,  as  above  defined,  from  asphalte  and  bitumen.  This  bitumen  was 
at  first  obtained  from  the  asphalte  and  molasses  of  Seyssel  by  boiling  either 
the  broken  stone  or  sand  (of  the  molasses)  when  the  bitumen  separated, 
and  was  skimmed  off  the  surface  of  the  water  and  sides  of  the  boiler.  This 
bitumen  (after  being  re-melted  and  allowed  to  settle  to  clear  it  from  sand, 
if  necessary)  is  melted  in  an  iron  boiler  to  the  amount  of  between  5  and  10 
per  cent,  of  the  required  batch,  and  the  powdered  asphalte  added  slowly 
and  stirred  in  until  all  is  thoroughly  incorporated.  It  is  then  cast  in  molds 
for  sale  or  use  as  mastic.  When  this  mastic  is  used  it  is  necessary  to  break 
it  up  and  add  it  again  to  melted  bitumen,  after  which  50  to  60  per  cent,  of 
fine  or  coarse  silicious  sand  is  added,  and  the  whole  kept  heated  till  it  does 
not  stick  to  a  clean  wooden  stirrer. 

The  mastic  is  then  taken  to  the  place  where  it  is  to  be  laid,  in  a  locomo- 
bile, essentially  a  horizontal  cylinder  on  four  wheels,  with  a  fire-box  under 
it  and  an  arrangement  for  stirring  the  mastic  so  as  thoroughly  to  mix  the 
gravel  and  to  keep  the  mixture  from  burning.  It  is  then  laid  on  a  concrete 
foundation,  generally  for  sidewalks  YZ  inch  thick,  or  more.  It  is  poured 
on  the  concrete  from  conical  sheet-iron  pails,  and  spread  by  the  aid  of  a 
wooden  hand  float.  After  the  spreading  is  completed,  sand,  and  in  some 
instances  gravel  the  size  of  peas,  is  added,  and  the  surface  well  rubbed. 
The  sand  adds  to  the  wear  of  the  sidewalk,  and  prevents  the  mastic 
softening  under  the  heat  of  the  sun.  The  mastic  is  sometimes  laid  in  one 
course  and  sometimes  in  two. 


96     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

M.  Malo  insists  on  the  bitumen  used  for  mastic  being  the  same  as  that 
impregnating  the  limestone,  but,  on  account  of  its  scarcity,  it  has  been  al- 
most entirely  replaced  by  refined  and  tempered  Trinidad  or  other  bitu. 
men. 

Crude  Trinidad  contains,  besides  water,  chips,  leaves,  etc.,  twenty- 
five  to  thirty  per  cent,  of  clay,  in  which  state  it  is  brittle,  and  the  clay,  as 
in  the  case  of  compressed  asphalte,  is  an  element  of  weakness,  as  it  at- 
tracts water.  It  is  refined,  according  to  Malo,  "  with  goudron,"  a  product 
of  a  second  distillation  of  schists,  which,  at  a  temperature  of  59  degrees  to 
68  degrees  Fahrenheit,  has  the  aspect  of  a  completely  liquid  bitumen  ;  600 
to  700  pounds  of  this  goudron  is  boiled  in  a  chaldron,  in^o  which  the 
crude  bitumen,  broken  to  the  size  of  an  egg,  is  thrown  in  successive  doses 
until  the  weight  is  1,700  to  1,900  pounds.  After  the  ebullition  has  ceased 
the  fire  is  drawn  and  time  allowed  for  the  sand  and  earth  to  settle,  when 
the  purified  bitumen  is  drawn  off  and  strained.  The  mineral  tar  of 
Autun  is  said  to  be  the  best  substance  now  in  the  market  for  refining  and 
tempering  bitumen. 

M.  Malo  deprecates  the  use  of  oils  from  boghead  coal  and  petroleums 
generally.  All  of  the  manufacturers  interviewed  on  the  subject  denied  the 
use  of  still  bottoms  or  petroleums,  and  most  agreed  with  Malo  that  bog- 
head oils  should  not  be  used,  on  account  of  the  cracks  which  occurred  in 
the  mastic ;  others  claimed  that  the  cracks  were  due  either  to  a  poorer 
quality  of  asphalte  than  they  used,  or  to  an  insufficient  purification  of  the 
Trinidad.  See  also  App.  No.  4,  art.  17,  and  App.  No.  5,  art.  21. 

There  is  a  great  difference  between  the  true  asphaltic  mastics,  depend- 
ing on  the  purity  and  quality  of  the  asphalte,  the  purity  and  component 
parts  of  the  goudron,  and  the  skill  of  manipulation.  A  well-made  mastic 
is  decidedly  harder  than  compressed  asphalte,  which  to  a  certain  extent  is 
partially  fluid  under  pressure,  and  increases  in  density  under  traffic  much 
faster  than  the  surface  is  abraded.  Mastic,  on  the  other  hand,  as  above 
stated,  is  hard,  crumbling  under  too  great  pressure,  not  noticeably  com- 
pressible, but  disintegrating  under  the  blows  of  horses'  feet.  It,  however, 
has  much  more  cohesion  than  compressed  asphalte,  and  should  be  pre- 
ferred in  those  situations  where  it  is  not  liable  to  receive  the  compressive 
action  of  heavy  loads,  and  is  exposed  in  large  areas  to  changes  of  tem- 
perature ;  the  partial  fluidity  of  asphalte  keeps  such  cracks  closed  under 
traffic. 

In  the  courts  of  the  new  House  of  Parliament,  eighty  by  forty-six  feet, 
Claridge's  mastic  stands  without  cracks,  a  beautiful  surface  ;  while  care- 
fully laid  compressed  asphalte  in  the  court  next  to  it  has  cracks  in  its  sur- 
face. Claridge's  asphaltic  mastic,  which  has  a  very  high  reputation  in 
London,  is  made  from  Seyssel  asphalte  and  a  very  carefully  refined  Trini- 
dad goudron.  It  is  claimed  that  the  Trinidad  bitumen,  when  thoroughly 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    97 

cleared  of  its  clay,  has  the  greatest  cohesive  strength  of  any  of  the  bitu- 
mens, and  the  Claridge  Company  claim  that  they  conduct  their  refining 
processes  with  more  skill  and  thoroughness  than  any  other  company. 
Their  mastic  is  laid  in  two  courses  in  strips  about  3  feet  wide,  breaking 
joints. 

It  is  believed  that  in  Paris  no  compressed  asphalte  is  laid  for  side- 
walks, but  in  London  the  Limmer  Company  is  compressing  Sicilian  on 
sidewalks,  and  the  Val  de  Travers  Company  always  use  compressed. 

Some  mastic  was  laid  in  London  streets,  but  it  is  now  being  rapidly 
repaired  or  renewed  with  compressed  asphalte,  except  in  narrow  streets 
of  small  traffic,  nor  is  asphaltic  mastic  laid  in  the  wheelways  of  Paris. 

There  is  one  theoretical  point  in  regard  to  different  asphaltes  to  which 
the  attention  of  the  Society  may  be  called.  That  is  the  fact  that  some 
asphaltes  will  compress  and  others  will  only  make  mastics.  The  Val  de 
Travers  and  the  Seyssel  are  very  good  for  either  purpose.  Lobsan  is 
capable  of  being  compressed,  and  with  proper  treatment,  making  a  mastic. 
Sicilian,  as  far  as  known,  has  only  been  employed  for  compression.  The 
asphaltes  of  Hanover  and  Brunswick,  while  they  make  very  good  mastics, 
seem  incapable,  with  the  present  knowledge,  of  being  compressed,  and 
the  writer  has  met  no  one  who  could  explain  the  cause  of  the  differences. 
It  evidently  does  not  lie  in  the  quantity  of  bitumen  contained  in  the  rock, 
as  some  Hanover  asphaltes  contain  more  than  either  the  Seyssel  or  the 
Val  de  Travers. 

BITUMINOUS  MASTIC. 

Bituminous  mastics,  or  the  fictitious  mastics  of  Malo  and  the  French 
writers,  were  experimented  with  very  generally  in  Europe,  in  the  hope  of 
finding  something  as  useful  as  asphalte  at  a  less  price  ;  but  it  was  found 
that  no  practicable  degree  of  heat  and  pressure  would  give  the  microscopic 
impregnation  of  grain  found  in  the  natural  mineral. 

In  this  country  the  effort  took  a  different  direction.  Refined  and  prop- 
erly tempered  Trinidad  bitumen  was  mixed  with  limestone  or  fine  or  coarse 
sand,  and  a  product  was  sought  between  asphalte  and  asphaltic  mastic. 
It  is  applied  neither  as  a  dry  powder  nor  in  a  fluid  or  semi-fluid  condition, 
but  as  a  sticky  and  coherent  mass,  and  is  subjected  to  pilonnage  and  roll- 
ing. While  it  does  not  seem  to  have  either  the  ductility  under  traffic  or 
the  resistance  to  wear  of  asphalte,  it  has  less  hard  brittleness  than  the 
true  asphaltic  mastic  ;  its  great  difficulty  being  a  tendency  to  disintegrate 
in  a  rotten  manner,  possibly  from  the  use  of  improper  oil  in  refining  and 
tempering  the  Trinidad  bitumen,  or  else  from  the  inherent  difficulty  of 
making  an  artificial  mixture  equal  in  quality  to  the  natural  product. 

The  most  successful  pavement  of  this  class  in  this  city  is  the  block  on 
Fifth  avenue  opposite  the  Worth  Monument,  laid  by  the  "  Grahamite 
Company."  Its  component  parts  are  understood  to  have  been  a  mixture 


98     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

of  Trinidad  bitumen  with  fine  sea  sand  containing  a  little  carbonate  of 
lime,  and  enough  Grahamite  or  Ritchie  mineral  "  to  save  the  patent." 
This  pavement  was  laid  in  the  spring  of  1873,  and  after  the  rectification 
of  surface  generally  necessary,  it  stood  till  the  fall  of  '77  without  requir- 
ing any  repairs  that  could  be  charged  to  its  own  weakness.  It  was  re- 
paired by  another  company  in  the  fall  of  1878,  and  now  requires  addi- 
tional attention.  During  this  time  it  has  filled  all  the  conditions  demanded 
of  a  good  pavement  to  a  greater  extent  than  any  other  pavement  in  the 
city.  Three  other  pieces  laid  by  this  company  have  not  proved  so  suc- 
cessful. 

Pavements  of  this  class  are  very  fully  described  in  General  Gilmore's 
Roads,  Streets  and  Pavements. 

They  are  being  extensively  laid  in  Washington  under  a  contract  for 
three  years'  maintenance.  As  in  France  and  England,  it  is  held  that 
whatever  the  physical  properties  and  composition  of  an  untried  asphalte 
may  be,  it  is  not  safe  to  pronounce  it  a  success  until  after  three  years'" 
wear ;  it  seems  that  a  longer  maintenance  contract  would  be  advisable. 

In  London,  Colonel  Haywood,  as  noticed  under  the  head  of  Wood 
Pavements,  lets  his  asphalte  pavements  at  a  certain  price  per  square  yard 
for  laying,  and  a  provision  that  they  shall  be  maintained  for  2  years  at 
the  contractor's  expense  and  1 5  years  at  an  agreed  price  per  square  yard 
per  annum,  and  a  good  pavement  be  given  to  the  city  at  the  end  of  the 
17  years. 

Several  different  kinds  of  pavements,  compressed  and  fictitious  and 
other  mastics,  were  laid,  the  Val  de  Travers  compressed  asphalte  being 
the  only  one  that  was  satisfactory,  and  most  of  the  other  pavements  were 
relaid  by  that  company  at  the  expense  of  the  sureties.  The  Limmer  & 
Vorwohle  Company,  however,  introduced  the  use  of  Sicilian,  with  which 
they  have  relaid  Newgate  and  Aldgate  streets,  and  are  relaying  Cornhill. 

In  the  City  of  Jassy,  Roumania,  the  contract  (see  Appendix  No.  5)  is 
based  on  the  London  plan.  The  work  was  commenced  in  1873  and  fin- 
ished in  1878.  It  is  to  be  maintained  at  the  contractor's  expense  until 
1880,  from  that  time,  and  until  1895,  at  a  stipulated  price. 

In  Paris  (see  Appendix  No.  4)  the  system  is  to  let  the  construction, 
maintenance,  and  repairs  of  pavements  and  footpaths  for  a  term  of  years, 
5  to  10,  without  guarantee  of  wear,  relying  on  rigorous  specifications  and 
thorough  inspection  for  the  excellence  of  the  work. 

The  plan  pursued  in  London  and  Jassy  seems  preferable,  even  with  the 
natural  asphaltes,  for  after  the  solidity  of  the  foundation  is  assured,  the 
duration  of  the  wheelway  depends  so  much  on  the  technical  skill  and 
thorough  honesty  exhibited  in  small  details,  that  the  burden  of  proper 
inspection  should  be  thrown  on  the  contractor  by  his  having  a  large 
pecuniary  interest  in  the  soundness  of  the  work  done  and  material  fur- 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    99 

nished.  The  inspection,  however,  should  be  close  enough  to  keep  the 
engineer  in  charge  fully  informed  of  the  methods  and  materials  em- 
ployed, particularly  towards  the  close  of  the  contract.  But  no  greater 
injury  could  be  done  to  a  city's  system  of  streets  than  strictly  enforcing 
the  specifications  of  some  of  the  300  and  more  patents  taken  out  for 
mastic  pavements. 

The  possibility  of  having  any  street  in  continuous  good  order  for  17 
years  is  probably  too  much  for  the  imagination  of  the  average  New 
Yorker.  And  no  one  can  well  realize  the  effects  of  having  all  the  streets. 
so  kept  in  repair. 

TAR  MASTIC. 

Among  the  legacies  of  the  "  ring"  were  the  various  tar  pavements. 
They  were  worse  than  the  wood  pavements,  though  not  being  so  thick, 
they  have  not  proved  so  enduring  a  nuisance  as  the  latter. 

The  best  of  them  are  understood  to  have  been  made  of  crude  coal  tar 
mixed  with  gravel  and  sand,  and  on  the  evaporation  of  the  light  oils  they 
went  to  pieces,  generally  with  great  celerity.  Occasionally  a  patch  would 
be  found  that  stood  the  traffic  pretty  well ;  this  was  supposed  to  result 
from  the  evaporation  of  the  oils  before  mixing  with  the  gravel.  G. 
Leverich,  Member  of  the  Society,  proposed  to  secure  a  uniform  product 
by  passing  steam  of  a  certain  temperature  through  the  tar  and  driving  off 
all  the  oils  of  low  specific  gravity.  Coal  tar  is  now  generally  reduced  to 
pitch  to  get  the  aniline  colors,  their  most  valuable  product,  and  the  pitch 
may  be  tempered  by  melting  with  dead  oils,  a  waste  product  of  the  dis- 
tillation. It,  however,  is  very  brittle,  and  it  is  doubtful  if  it  can  be  em- 
ployed economically,  except  for  side-walks  of  light  traffic. 


ioo  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 


APPENDIX    NO.  i. 
Extract  from  Specification  of  W.  S.  Till,  Borough  Surveyor,  Birmingham,  1877. 

The  whole  of  the  carriage  way  to  be  excavated  to  the  required  depth,  and  the  foundations 
formed  to  uniform  gradients  and  proper  cross  sections,  with  ashes  or  other  approved  materials. 
When  these  have  been  rolled  and  are  well  set,  the  contractor  to  coat  the  whole  width  and  length 
of  the  carriage  way  with  not  less  than  8  inches  of  good,  strong,  clean  gravel,  screened  through  a 
J-inch  riddle,  or  with  not  less  than  8  inches  of  approved  slag,  broken  regularly  to  such  a  size  that 
the  largest  piece,  on  its  greatest  dimension,  will  pass  through  a  3-inch  ring. 

The  gravel  or  slag  to  be  well  gritted  and  watered,  and  kept  raked  togethei  and  rolled  until 
the  whole  is  consolidated.  ********* 

The  contractor  to  coat  the  carriage  way,  throughout  its  whole  length  and  width,  with  not  less 
than  6  inches  of  Eowley  flagstone,  broken  to  pass  throngh  a  2Hnch  ring. 

The  stone  to  be  gritted,  watered,  and  kept  together,  raked  and  rolled  until  the  whole  is  con- 
solidated. Crown  6  inches  above  curbstone.  Each  layer  to  be  laid  on  complete  throughout  the 
whole  length  and  width  of  carriage  way,  and  each  layer  to  be  separately  rolled  with  a  heavy 
roller. 

APPENDIX    NO.  2. 

Extract  from  Specification  for  TeTford,  Macadam  and  Trap  Block  Gutters  on 

Fifth  Avenue. 

(4).  DESCRIPTION  OP  MATERIALS. — The  stone  blocks  are  to  be  of  double  and  uniform  quality, 
each  measuring,  on  the  face  or  upper  surface,  not  less  than  4  nor  more  than  8  inches  in  length, 
and  not  less  than  4  nor  more  than  6  inches  in  width,  and  in  depth  not  less  than  6  nor  more  than  8 
inches  ;  blocks  of  4  inches  in  width  on  the'r  face  to  be  not  less  than  3  inches  in  width  at  the  base; 
all  other  blocks  on  transverse  measurement  on  the  base,  to  be  not  more  than  2  inches  less 
than  on  the  face,  but  no  block  on  the  base  shall  be  of  less  width  or  length  than  3  inches,  and  to 
be  in  all  respects  equal  to  the  specimen  blocks  at  the  office  of  the  Commissioner  of  Public 
Works. 

It  is  also  required  that  the  sides  of  the  stones  (which  form  the  joints)  shall  be  so  sufficiently 
even  and  properly  shaped  that  joints  may  be  formed  with  a  similar  side  not  exceeding  J  of  an 
inch,  no  stone  having  an  objectionable  protruding  face  will  be  accepted  or  allowed  to  be  used  for 
paving.  They  will  be  carefully  inspected  after  ttfey  are  brought  on  the  line  of  the  work,  and  all 
blocks  which,  in  quality  and  dimensions,  do  not  conform  strictly  to  these  specifications,  will  be 
rejected,  and  must  be  immediately  removed  from  the  line  of  the  work.  The  contractor  will  be 
required  to  furnish  such  laborers  as  may  be  necessary  to  aid  the  inspector  in  the  examination 
and  culling  of  the  blocks  ;  and  in  case  the  contractor  shall  neglect  or  refuse  so  to  do.  such  labor- 
e.s  as  in  the  opinion  of  the  Commissioner  of  Public  Works  may  be  necessary,  will  be  employed 
by  the  said  Commissioner,  and  the  expense  thus  incurred  by  him  will  be  deducted  and  paid  out 
of  any  money  then  due  or  which  may  hereafter  grow  due  to  the  said  contractor  under  this  agree- 
ment. The  blocks  must  be  of  trap  rock  or  of  syenite,  equal  in  hardness  to  what  is  called  Quincy 
granite. 

TELFORD.— The  stone  for  the  foundation  of  the  pavement  is  to  be  sound,  hard  and  durable 
quarry  stone,  each  from  eight  to  ten  inches  in  depth,  from  three  to  six  inches  in  width,  and  from 
six  to  fourteen  inches  in  length,  and  of  a  sufficiently  uniform  size  to  fce  acceptable ;  except  the 
stone  under  the  gutters,  which  only  differ  from  those  above  described  in  that  they  must  be  not 
less  than  six  inches  in  depth,  and  except  the  course  of  stone  under  the  Macadam,  which  is  next 
to  the  gutters  or  the  bridge  stone,  which  stone  is  to  be  twelve  inches  in  depth,  and  in  every 
other  respect  as  first  above  described. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  101 

The  broken  stone  for  the  bottom  course  is  to  be  of  trap  rock,  and  of  such  size  that  would 
pass  in  any  direction  through  a  ring  with  interior  diameter  of  2^  inches,  and  of  a  sufficiently  uni- 
form size  and  proper  shape  to  be  acceptable,  to  be  composed  only  of  stone  that  is  hard  and 
durable,  and  sufficiently  free  from  screenings,  and  practically  free  from  dirt  aad  other  foreign 
matter.  The  broken  stone  composing  the  next  overlying  course  is  to  be  the  same  in  every  respect 
as  just  described,  except  that  each  stone  is  to  be  of  such  size  that  would  pass  In  any  direction 
through  a  ring  with  interior  diameter  of  2  inches. 

The  coarse  screenings  are  to  be  those  of  trap  rock  ;  the  stone  Is  to  be  practically  free  from 
dirt  and  other  foreign  matter,  to  be  composed  of  material  only  that  is  hard  and  durable,  no  particle 
of  which  is  to  be  of  larger  size  in  any  direction  than  1|  inches,  and  all  the  particles  to  be  of  such 
relative  size  to  \\  inches  as  shall  be  acceptable;  through  these  screenings  is  to  be  evenly  mixed 
before  rolling  a  sufficient  quantity  of  the  finer  screenings  of  trap  rock  to  form  a  proper  ani  secure 
bond. 

The  fine  screenings  of  trap  rock  are  to  be  practically  free  from  dirt  and  other  foreign  matter, 
and  to  be  composed  of  material  both  as  to  size  and  quality  that  will  be  acceptable. 

(9).  PREPARATION  OF  EOAD  BED,  &c. — All  pavir.g  and  other  stones  necessary  to  be  removed 
shall  be  taken  up  and  immediately  removed  from  the  line  of  the  work ;  the  Belgian  and  granite 
blocks  to  be  deposited  where  directed  by  the  Water  Purveyor  for  the  use  of  the  city;  the  subsoil 
or  other  matter  (be  it  earth,  rock  or  other  material)  shall  then  be  excavated  and  removed,  to  such 
depth  to  be  determined  by  the  engineer  in  charge,  that  when  rolled  and  finished,  irrespective  of 
the  covering  of  fine  screenings,  the  pavement  throughout  its  entire  extent  shall  be  at  least 
sixteen  inches  thick.  Should  there  be  any  spongy  material  or  vegetable  matter  in  the  bed  thus 
prepared,  all  such  material  shall  be  removed,  and  the  space  filled  with  clean  gravel  or  sand  care- 
fully rammed  or  rolled,  so  as  to  make  such  filling  compact  and  solid.  No  ploughing  will  be 
allowed  in  preparing  the  foundation. 

The  road  bed  shall  be  truly  shaped  and  trimmed  to  the  required  grade,  and  with  such  crown 
as  shall  be  directed  by  the  said  engineer,  and  rolled  with  a  roller  weighing  not  less  than  two  tons, 
until  the  surface  is  firm  and  compact. 

LAYING  THE  FOUNDATION  OR  PAVEMENT. — After  the  road  bed  is  prepared,  agreeably  to  the 
terms  of  this  specification  and  to  the  satisfaction  of  the  engineer,  and  the  stone  hauled  and  de- 
posited thereon,  the  foundation  stones  shall  be  laid  by  hand  in  the  form  of  a  close,  firm  pavement, 
They  shall  be  set  on  their  broadest  edges  and  lengthwise  across  the  road,  except  in  the  case 
of  the  stone  under  the  Macadam,  which  is  next  the  gutter  stones  or  bridge  stones,  which 
foundation  stone  is  to  be  placed  with  its  longest  side  parallel  to  the  curb  or  bridge  stone* 
after  being  set  closely  together,  they  are  to  be  firmly  wedged  by  inserting  and  driving  down 
with  a  bar,  in  all  possible  places  between  them,  stones,  as  near  as  practicable,  of  the  same 
depth,  until  all  the  stones  are  bound  and  clamped  in  proper  position;  all  the  projections  and 
irregularities  of  the  upper  part  of  the  pavement  shall  then  be  broken  off  with  a  hammer,  care 
being  taken  not  to  loosen  the  pavement,  and  the  spalls  and  chips  are  to  be  worked  and 
driven  with  the  hammer  into  all  the  interstices  not  already  filled  by  the  process  of  wedging,  so 
that  the  pavement,  when  completed,  shall  present  a  sufficiently  even  surface,  and  be  at  each 
point  of  such  thickness  as  required  by  these  specifications.  No  wedging  shall  be  done  within 
twenty- five  feet  of  the  face  of  the  work  that  is  being  laid,  and  the  stone  foundation  must  be  ia 
a  compact  and  satisfactory  condition  in  every  respect  at  the  time  of  the  spreading  of  the  broken 
stone. 

MACADAMIZING. — After  the  stone  foundation  has  been  completed  agreeably  to  these  speci- 
fications, and  has  passed  the  inspection  of  the  said  engineer,  a  layer  of  broken  stone  of  the  quality 
and  size  herein  specified  for  the  bottom  course,  and  of  such  a  depth  as  will  make  4  inches  when 
rolled,  shall  be  spread  evenly  over  the  pavement  ;  this  layer  is  then  to  be  rolled  until  sufficiently 
compact. 

The  next  overlying  course  will  be  of  stone,  as  hereinbefore  described  for  said  course,  and  is  to 
be  spread  so  that  the  surface  will  be  uniformly  1  inch  below  the  grade  and  crown  when  the  pave- 
ment is  finished. 

Stone  hammers  are  to  be  used  on  this  course,  so  that  when  rolled  as  much  as  shall  be  re- 
quired the  surface  of  each  stone  that  is  exposed  will  not  have  a  longer  dimension  in  any  direction 
than  1  inch. 


102  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

A  layer  consisting  of  the  coarse  screenings  herein  specified  is  then  to  be  applied  and  spread  to 
such  depth  as  will  bring  the  surface  to  the  proper  grade,  irrespective  of  the  finish  of  fine  screen- 
ings; this  layer  is  then  to  be  rolled,  and  during  the  progress  of  the  rolling,  if  necessary,  coarse 
screenings  shall  from  time  to  time  be  applied,  so  that  when  the  rolling  ceases  the  roadway  is  truly 
surfaced  to  the  required  grade  and  crown.  This  layer  is  to  be  rolled  until  all  settlement  ceases  and 
the  stones  are  thoroughly  compact  and  the  surface  true  to  the  grade  and  crown . 

During  the  process  of  rolling  any  course  of  stone  there  shall,  Avhen  required,  be  spread 
lightly  over  the  same  from  a  shovel,  the  fine  screenings  of  trap  rock  herein  described  ;  and  after 
the  upper  layer  has  become  thoroughly  compact,  there  shall  be  spread  upon  the  surface  fine 
screenings,  so  much  as  to  produce  a  covering  half  an  inch  in  depth  when  rolled,  and  the  rolling 
is  to  continue  until,  by  a  sufficient  use  of  water,  a  wave  is  produced  before  the  wheel  of  the 
roller. 

The.rolling  of  the  Macadam  stone  and  screenings  shall  be  done  with  a  roller  weighing  not  less 
than  any  of  the  steam  rollers  in  the  possession  of  the  Department  of  Public  Works. 

Each  layer  of  broken  stone  and  the  screenings  or  binding  material  shall  be  Avell  and 
thoroughly  rolled,  and  the  rolling  upon  each  layer  shall  be  prosecuted  until,  in  the  opinion  of 
the  engineer,  each  course  shall  have  been  completed,  as  hereinbefore  specified,  and  until  each 
layer  and  the  finished  surface  shall  be  rolled  and  finished  to  his  entire  satisfaction  and  approval. 

While  the  rolling  of  each  layer  of  broken  stone  and  the  screenings  or  binding  material  is 
being  presecuted  the  work  shall  be  kept  moistened  to  such  extent  and  in  such  manner  as  re- 
quired, and  care  shall  be  taken  that  too  much  water  is  not  applied  while  rolling  the  first  layer, 
-and  until  after  the  interstices  are  well  filled  with  the  binding  material. 

The  pavement,  when  completed,  shall  be  at  each  point  of  such  construction  and  at  least  of 
such  a  depth  as  required  by  the  specifications,  and  of  such  crown  and  such  form  of  gutter  as 
shall  be  directed,  and  in  any  case  the  thickness  of  the  pavement  is  to  be  determined  on  a  line  at 
right  angles  to  the  grade  and  crown. 

The  use  of  a  proper  roller,  rammers,  or  other  suitable  implement,  is  to  be  substituted  for 
that  of  the  steam-roller  when  necessary. 

The  construction  of  the  foundation  stones,  and  the  Macadam  pavement  shall  proceed  so  as  to 
l>e  practically  equally  as  far  advanced  across  the  entire  width  of  said  pavements. 

Particular  care  and  attention  will  be  required  in  obtaining  a  satisfactory  joining  of  the  Ma- 
•cadam  paving  and  the  blocks  in  the  gutters. 

PAVING  THE  GUTTERS. — Upon  the  stone  foundation  already  described,  shall  be  laid  a  bed  of 
•clean,  sharp  sand,  not  too  fine,  or  clean  fine  gravel,  of  the  depth  necessary  (about  4  inches)  to 
bring  the  paving  to  the  proper  shape  and  grade  when  rammed.  The  stone  blocks  are  to  be  laid 
with  joints  at  right  angles  to  the  curb,  with  joints  not  exceeding  three-quarters  of  an  inch,  at 
such  grade  and  in  such  form  as  shall  be  directed  ;  each  course  of  blocks  shall  be  of  a  uniform 
width  and  depth,  and  so  laid  that  all  longitudinal  joints  shall  be  broken  by  a  lap  of  at  least  one 
inch  ;  and  the  blocks  next  the  curb  shall  break  joints  with  the  curb  by  at  least  one  inch ;  as  the 
blocks  are  laid  the  joints  shall  be  so  filled  with  sand  or  gravel  as  to  secure,  when  the  work  herein 
mentioned  is  completed,  against  there  being  any  spaces  not  filled  with  sand  or  gravel  between 
the  blocks  ;  they  shall  be  covered  with  clean,  sharp  sand,  which  shall  be  raked  until  the  joints 
"become  filled  therewith,  the  blocks  shall  then  be  thoroughly  rammed  to  a  firm  unyielding  bed, 
•with  a  uniform  surface  to  conform  to  the  grade  and  crown  of  the  avenue,  as  shall  be  directed. 
No  ramming  shall  be  done  within  25  feet  of  the  face  of  the  work  that  is  being  laid  ;  and  the  ram- 
ming is  to  be  done  at  such  times  and  in  such  manner  with  reference  to  the  rolling  as  shall  be 
•directed.  When  the  paving  from  the  centre  of  an  intersecting  street  to  the  centre  of  the  next 
intersecting  street  is  constructed,  it  shall  be  covered  with  a  good,  sufficient  second  coat  of  clean 
sand,  and  shall  immediately  thereafter  be  thoroughly  rammed  until  the  work  is  made  solid  and 
secure,  and  so  on,  until  the  whole  of  the  work  embraced  in  this  contract  shall  have  been  well  and 
faithfully  completed  in  accordance  therewith. 

This  portion  of  the  work,  laid  with  trap  blocks  for  the  gutters,  will  be  measured  and  in- 
-cluded  in  the  returns  for  Macadam  pavement. 

No  stone  or  other  material,  except  sand  or  granite,  is  to  be  placed  on  the  blocks  that  are 
paved,  until  these  are  rammed.  When  necessary,  in  order  to  make  good  joints,  the  blocks  are  to 
be  trimmed  down  on  the  sides  by  and  at  the  expense  of  the  contractor.  „ 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  103 
APPENDIX    NO.    3. 

ROAD    BOLLEBS. 

As  far  as  known  to  the  writer,  the  4  rollers  here  described  are  the  only  ones  in  the  market ; 
they  all  run  with  equal  facility  with  either  end  forward. 

THB   GELLERAT   ROLLER. 

These  machines  consist  essentially  of  a  locomotive  boiler,  supported  on  a  frame  which  is  car- 
ried on  two  cast-iron  rollers,  each  8  feet  11  inches  in  diameter,  and  4  feet  7  inches  long  for  the  15- 
ton  rollers,  and  4  feet  9  inches  in  diameter  and  6  feet  long  for  the  80-ton  rollers.  Their  peculiarity 


THE  GELLERAT  ROLLER. 


104  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

is  that  each  roller  is  a  driving  wheel,  and  bears  half  the  weight  of  the  machine,  which  is  guided  by 
a  hand  wheel  working  from  the  foot-board  into  a  bevel  gear  S,  Fig.  2,  which  works  the  right  and 
left  hand  screws,  R  H,  throwing  the  axes  of  the  rollers  into  radial  positions;  the  other,  or  driving 
end  of  each  axle,  is  stationary,  with  a  spherical  bearing— Figs.  1  and  2. 

THB   LINDELOF  BOLLEB. 

This  roller  has  an  upright  boiler,  and  two  vertical  cylinders  that  actuate  a  beveled  gear  which 
works  into  a  gear  bolted  on  to  the  driving  wheel,  the  tread  of  which  is  a  1-inch  plate  of  wrought 
iron  ;  the  driving  roller  bears  two-thiids  of  the  weight  of  the  machine.  Both  10  and  15-ton  rollers 


THE  LINDELOF  STEAM   ROAD  ROLLER. 


are  built ;  for  the  10  ton,  of  2,000  pounds  each,  the  driving  roller  is  6  feet  and  the  steering  roller  5 
feet  long,  giving  a  weight  on  the  driving  roller  per  inch  run  of  185  pounds. 


THE  AVELING  AND  POBTEB  BOLLER. 

This  roller,  which  is  extensively  used  in  this  country,  has  been  improved  in  several  par- 
ticulars, and  is  believed  to  be  the  only  roller  now  in  the  market  that  is  run  and  fired  by  one  man. 

As  now  manufactured  the  outside  wheels  are  the  driving  wheels,  the  steering  wheels  covering 
the  space  between  thorn.  The  boiler  is  horizontal  and  multitubular  ;  the  single  steam  jacketed 
cylinder  is  on  top  of  the  boiler,  and  runs  a  fly-wheel  which  by  the  aid  of  Bearing  drives  the  roller 
at  a  speed  of  about  2  miles  per  hour.  The  driving  wheels  have  holes  in  their  treads  in  which 
spikes  may  be  placed  for  tearing  up  the  road  bed  before  remetalling,  and  the  fly-wheel  makes  the 
roller  available  as  a  stationary  engine  to  run  a  stone  breaker. 

Four  sizes  are  manufactured,  viz.,  8, 10,  15  and  20  tons  in  weight.  Two-thirds  of  the  weight 
is  carried  on  the  driving  wheels,  which  have  a  width  of  2  feet  2  inches  for  the  20-ton  roller,  giving 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS,  105 


106  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

a  weight  per  inch  run  of  574  pounds  ;  the  width  of  driving  wheels  on  the  15-ton  roller,  is  1  foot  10 
inches,  giving  a  weight  per  inch  of  509  pounds.    The  roller  is  fitted  with  a  friction  brake. 

THE   E088   BOLLER. 

This  machine  is  a  combined  road  roller  and  rammer.     Only  one  size  is  built,  weighing  44,000 
pounds.    The  boiler  is  vertical  and  the  rams,  any  or  all  of  which  can  be  used  or  not,  are  actuated 


T>y  cams.  The  length  of  the  driving  roller  is  6  feet  in  all,  with  a  space  in  the  middle  of  8  inches 
for  the  driving  chain.  The  steering  roller  is  30  inches  long.  Four-fifths  of  the  entire  weight  is 
carried  by  the  driving  wheel,  giving  a  compressive  force  per  inch  run  of  550  pounds.  It  is  claimed 
that  the  traction  is  sufficient  to  allow  it  to  mount  grades  of  20  feet  per  100.  Maximum  speed,  5 
miles  per  hour. 

The  rains,  five  in  number,  are  said  to  give  an  effective  blow  of  7,000  pounds  each ;  they  are  of 
no  use  in  compressing1  and  puddling  trap,  but  are  efficient  with  limestone,  and  must  be  efficacious 


CONSTRUCTION  AND  MAINTENANCE  OF  ROAD.S.  107 

for  rubble  foundations.    The  frame  is  utilized  as  a  water  tank,  and  the  driving  roller  can  be 
heated  by  steam  for  rolling  mastics,  &c. 

APPENDIX  No.  4. 

A  part  of  the  Contract  for  the  Construction  and  Maintenance  of  the  Streets  and 
Sidewalks  of  the  City  of  Jassy. 

Between  M.  Nicholas  Gane,  Mayor  of  Jassy,  and  Mr.  W.  O.  Callender,  of  London. 

ARTICLE  1.  The  contract  has  for  its  objects  : 

(a.)  The  construction  of  a  system  of  streets  with  gutters  and  a  system  of  side  walks  with  curbs. 

(6.)  The  maintenance  of  the  streets  and  sidewalks  constructed  under  this  contract. 

ART.  2.  The  construction  consists  of  the  following  items  of  work  : 

<a.)  The  construction  of  47,853.8  square  yards  of  streets,  covered  with  compressed  asphalte. 

(6.)  The  construction  of  179,384.3  square  yards  of  sidewalks,  covered  with  asphaltic  mastic. 

(g.)  The  construction  of  17,038.4  square  yards  of  roadway,  paved  with  Macadam  made  from 
stone  taken  from  streets  now  paved. 

(h.)  The  construction  of  49,210  lln.  feet  of  granite  curbing  for  bordering  the  asphaltic  mastic 
sidewalks  on  streets  covered  with  compressed  asphalte. 

ART.  3.  The  time  fixed  for  the  completion  of  this  contract  is  five  years,  to  begin  with  July 
1st,  1873,  and  to  end  on  March  31st,  1878. 

ART.  5.  The  labor  of  maintenance  will  consist  in  maintaining  the  streets  in  a  constant  good 
-condition.  On  all  the  streets  and  sidewalks  constructed  by  him,  the  contractor  will  repair,  with 
his  own  laborers  and  his  own  material,  all  degradations  as  soon  as  they  appear,  and  will  replace 
the  material  lost. 

ART.  <>.  The  length  of  the  contract  for  maintenance  is  fixed  at  15  years,  to  begin  on  May  1st, 
1880,  and  to  end  on  April  80th,  1895. 

ART.  10.  The  transverse  inclination  of  the  asphalte  sidewalks  will  be  2  per  cent. 

ART.  11.  The  curbs  of  sidewalks  of  asphalte,  on  asphalted  streets,  will  be  of  granite ;  those  of 
sidewalks  t-f  asphalte,  on  streets  paved  with  blocks  or  cobble  stones,  will  be  of  sandstone,  and 
the  curbs  of  Macadam  steeets,  when  they  protect  sidewalks  of  the  same  material,  will  be  of  stone 
cut  from  the  old  flagstones  of  the  present  sidewalks. 

The  curbstones  will  be  of  the  following  dimensions:  The  faces  parallel  to  the  surface  of  the 
sidewalks  will  be  5.5  inches  in  width,  of  which  0.9  inch  of  the  upper  face  will  be  eventually 
covered  with  asphalte.  They  will  have  a  height  of  11.9  inches,  of  which  6  inches  will  be  under 
ground  and  the  remainder  above  the  gutter  ;  their  length  will  not  be  less  than  15|  inches.  The 
form  of  the  curb  will  be  that  of  a  parallelopipedon,  having  next  the  sidewalk  a  rebate  of  0.9  inch 
in  width  and  a  height  equal  to  the  thickness  of  the  bed  of  asphalte. 

ART.  14.  The  gutters  of  asphalted  streets  shall  have,  according  to  the  locality,  a  maximum 
width  of  3.3  feet ;  they  shall  be  constructed  of  new  cobble  stones,  well  culled,  or  of  new  sand- 
stone blocks.  At  the  edge  of  the  asphalte  there  will  always  be  laid  a  range  of  granite  blocks  10.6 
inches  in  length,  5.3  inches  in  width  and  9  inches  in  depth. 

ART.  15.  The  sandstone  blocks  for  the  gutters  will  be  dressed  to  regular  cubes  in  form,  of  9 
inches  on  eacb  side. 

ART.  16.  The  asphaltic  rock,  which  must  be  natural  and  not  artificial,  must  be  from  the  best 
asphaltic  quarries  known:  Liminer,  in  Hanover,  Seyssel,  in  France,  and  Val-de-Travers,  in  SwJtzer- 
lard.  The  asphaltic  mastic  to  be  used  must  satisfy  the  following  conditions  : 

(a.)  It  must  contain  12  parts  of  bitumen  to  88  parts  of  asphaltic  rock. 

(6.)  The  asphaltic  rock  itself  must  contain  at  least  7£  per  cent,  of  bitumen,  and  at  the  moat  93 
per  cent,  of  pure  carbonate  of  lime. 

(c.)  Eocks  which  contain,  even  in  small  proportions,  quartz,  sulphates,  iron  pyrites  or  alumi- 
num must  be  rejected  for  the  composition  of  mastic. 

ART.  17.  The  bitumen  used  for  mastic  must  be  natural,  not  artificial,  from  the  bitumen  lakes 
of  the  Island  of  Trinidad,  or  horn  the  asphaltic  rocks  of  Seyssel,  if  it  itJ  proved  to  be  equal  in 
quality  to  the  Trinidad  bitumen  :  it  must  be  free  from  water  ;  its  specific  gravity  must  be  from 
1.1  to  1.5.  Dipped  in  water  at  the  freezing  point,  it  must  not  lose  its  ductility  ;  ita  surface  must 


io8  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

present  no  cracks  or  streaks.  The  surface  of  a  fracture  must  be  black  and  brilliant.  It  must  be- 
perfectly  soluble  in  petroleum  oil  or  the  spirits  of  turpentine,  and  the  solution  when  passed 
through  a  filter  must  leave  DO  residue.  (?) 

ART.  18.  The  quarry  whence  comes  the  bituminous  rock,  the  mastic  and  the  bitumen,  must 
be  certified  by  authentic  certificates  to  be  of  even  fabric  and  its  products  of  the  first  quality. 
Each  block  of  mastic  must  bear  the  trade  mark  of  the  quarry. 

ART.  19.  The  contractor  is  forbidden  to  have  in  his  storehouses  any  asphaltic  rock  or  mastic 
which  do  not  comply  with  the  conditions  above  stated  and  not  in  conformity  with  the  samples 
deposited  with  the  Mayor  on  the  day  of  the  signing  of  this  contract ;  he  must  neither  use  nor 
have  in  bis  storehouses  any  bituminous  or  resinous  oils  other  than  those  specified  in  Article  17. 

All  other  material,  resinous,  bituminous  or  oleaginous  and  all  other  mastic  than  that  like  the 
samples  deposited  with  the  Mayor  that  may  be  found  in  the  storehouses  of  the  contractor  will,  on 
the  first  offense  be  confiscated,  and  a  fine  of  1,000  francs  be  imposed  ;  in  case  of  a  repetition  of 
the  offense,  confiscation  and  a  fine  of  5,000  francs;  and  should  it  occur  a  third  time,  beside  the 
confiscation,  the  contract  will  be  relet  at  the  expense  of  the  contractor's  surety. 

ART.  20.  The  gravel  employed  in  mixing  the  mastic  must  be  taken  from  the  beds  of  streams  ; 
it  must  be  thoroughly  cleansed  of  all  foreign  matter,  well  washed,  free  from  argillaceous  matter, 
and  must  be  passed  through  a  screen,  the  holes  of  which  do  not  exceed  0.2  inch. 

ART.  21.  The  sand  for  making  the  mortar  for  beton  and  for  forming  the  bed  for  asphalte,  even 
that  employed  for  bedding  the  street  pavements,  the  gutters  or  curbs,  shall  be  sharp,  hard  to  the 
touch,  and  will  be  procured  from  the  best  open  or  working  pits,  or  from  the  bed  of  running 
water. 

ART.  22.  The  cement  will  be  the  best  from  the  best  known  quarries,  such  as  Stefanesti  or 
Rodeni. 

ART.  23.  The  stone  used  in  mixing  the  beton  will  be  broken  stone  from  the  quarries  of  Paun 
or  Barnova.  Each  piece  must  pass  through  a  ring  of  2.4  inches  diameter  ;  it  shall  be  free  from 
all  foreign  matter  and  well  washed. 

ART.  24.  The  granite  shall  have  the  following  qualities  : 

(a.)  It  will  be  obtained  from  the  hardest  seams  of  the  quarries  ;  it  shall  be  homogeneous, 
sonorous  to  the  blow  of  a  hammer,  without  flaws  or  fractures  and  free  from  foreign  matter. 

(6.)  It  shall  have  a  specific  gravity  of  2.65. 

(c.)  After  an  immersion  of  24  hours  in  water,  it  must  not  absorb  more  than  SJ5  of  its  volume. 

(d.)  When  struck  a  hard  blow,  it  must  break  in  large  fragments  without  leaving  any  detritus. 

ART.  25.  The  sand  stone  shall  be  provided  from  the  hardest  beds  of  the  quarries  in  Eoumania. 
The  qualities  of  the  sandstone  shall  be  as  follows: 

(a.)  Under  the  blow  of  a  hammer  the  sound  of  the  stone  must  be  limpid  and  pure  ;  a  dull 
sound  would  indicate  interior  fissures,  and  would  be  sufficient  to  reject  it. 

(6.)  The  specific  gravity  shall  be  2.5. 

(c.)  After  an  immersion  of  24  hours  in  water,  it  should  not  absorb  more  than  ^j  oi  its  volume. 

ART.  26.  The  limestone  for  the  beton  shall  be  of  the  hardest  quality,  chosen  from  the  hardest 
beds. 

ART.  27.  The  mortar  for  the  beton  of  the  sidewalks  shall  be  composed  of  two  parts  of  sand 
to  one  part  of  cement  in  volume.  It  shall  all  be  mixed  and  wet  with  only  as  much  water  as  may 
be  absolutely  necessary.  Mortar  which  may  set  before  being  put  in  place  will  be  rejected. 
The  composition  of  the  mortar  for  the  beton  which  is  to  be  used  on  the  streets  remains  to  be 
described  hereafter,  as  also  the  compressed  asphalte. 

ART.  28.  The  beton  will  be  composed  of  three  parts  of  broken  stone  to  two  parts  of  mortar. 

The  betou  which  is  not  used  after  it  is  prepared  will  not  be  accepted. 

The  streets  which  are  to  be  covered  with  compressed  asphalte  shall  be  constructed  in  the 
following  manner : 

(a.)  The  levels  will  be  corrected,  the  ground  shall  be  shaped  to  the  form  of  the  transverse  pro- 
file fixed  by  the  city,  and  will  be  sprinkled  and  rolled  until  it  presents  a  smooth,  hard  surface. 

(6.)  The  curbstones  shall  then  be  set,  care  being  taken  to  cut  the  joints  on  the  ends  as  well 
as  on  the  front  edge. 

(c.)  The  part  corresponding  to  the  gutters  will  then  be  made  of  a  bed  of  sand  2.4  inches  in 
depth,  in  which  will  be  laid  the  stones  which  form  the  gutters  ;  the  sides  of  the  gutters  next  to  the- 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  109 

bed  of  asphalte  will  in  every  case  have  a  range  of  granite  blocks.  The  remainder  of  the  width  of  the 
gutters  shall  be  paved  with  cobble  stones,  well  assorted,  in  such  a  manner  that  the  stones  will  all 
be  of  the  same  size,  or  with  new  sandstone  blocks,  agreeably  to  the  city  authorities.  The  gutters 
thus  laid  shall  be  well  rammed  with  a  rammer,  and  over  all  shall  be  spread  a  layer  of  sand  0.4 
inch  deep. 

(d.)  That  portion  of  the  street  which  is  to  be  covered  with  asphalte,  will  receive  a  bed  of 
T>eton,  the  depth  of  which,  after  pilonnage,  shall  not  be  less  than  6  inches.  Upon  the  beton  shall 
be  spread  a  layer  of  brick  broken  to  0.4  inch  in  size. 

(e.)  On  this  shall  be  laid  the  compressed  asphalte,  when  the  foundation  shall  have  reached  the 
desired  consistency  and  become  well  dried. 

(f.)  The  asphalte  will  be  laid  according  to  the  methods  usually  adopted  on  works  of  a  similar 
nature  ;  the  method  of  doing  this  remains  to  be  discussed  at  a  future  day  by  the  city  and  the  con- 
tractor. 

ART.  83.  The  surface  of  the  sidewalks  shall  be  done  over  when  needed,  sprinkled  and  rolled  ; 
over  this  shall  be  laid  a  bed  of  beton  which  after  compression  shall  not  have  a  less  thickness  than 
3  inches.  On  this  shall  be  spread  the  mastic  to  a  depth  of  0.8  inch.  This  mastic  shall  be  com- 
posed of  asphaltic  mastic,  gravel  and  bitumen  in  the  following  proportions  :  Asphaltic  mastic  100 
parts,  gravel  60  to  72  parts,  and  bitumen  6  to  10  parts.  The  mastic  and  bitumen  shall  be  melted 
in  a  portable  kettle,  so  that  they  may  be  carried  to  the  spot  where  they  are  to  be  used.  The  mas- 
tic shall  be  broken  into  small  pieces,  and  shall  not  be  poured  until  it  is  entirely  melted.  During 
the  melting  the  mastic  shall  be  kept  stirred,  so  that  a  thorough  mixture  may  be  insured  and  the 
mastic  not  allowed  to  burn.  The  mastic  thus  prepared  shall  be  run  over  the  beton  in  such  a  man- 
ner as  to  spread  evenly  over  it.  Before  the  complete  solidification  of  the  mastic  which  forms  the 
surface,  sand  will  be  spread  over  it  and  fixed  by  light  ramming.  At  the  junction  between  a  cold 
and  a  hot  bed,  the  edge  of  the  cold  one  shall  be  reheated  by  spreading  over  it  a  coating  of  melted 
bitumen  that  will  then  be  removed  and  the  final  bed  laid. 

ART.  84.  The  tempering  of  the  mastic  should  be  such  that  it  will  support,  at  a  temperature 
of  77  Far.,  the  point  of  a  rectangular  pyramid  of  a  height  equal  to  one  side  of  the  base,  without 
a  depression  occurring  greater  than  0.2  inch  under  a  pressure  of  154  pounds  continued  for  five 
minutes. 

ART.  35.  The  sidewalks  at  carriage  doorways  shall  have  a  foundation  of  beton  4  inches  in 
depth  after  ramming,  and  the  bed  of  mastic  will  be  1.2  inches. 

ART.  87.  The  junction  of  the  mastic  with  the  walls  of  the  buildings  bordering  the  streets  will 
be  made  by  means  of  a  skirting,  that  is  to  say,  the  plaster  will  be  scraped  from  the  walls  of  these 
houses  to  a  height  of  2  inches  above  the  level  of  the  sidewalks,  and  the  asphalte  will  be  plastered 
on  the  bricks  to  the  thickness  of  the  mortar. 

The  junction  of  the  stratum  of  mastic  with  the  posts,  curbs,  hydrants,  and  other  objects  of 
various  natures  will  be  made  by  heating  these  objects  by  a  coating  of  melted  asphalte  that  will  be 
then  removed  and  the  final  bed  laid. 

ART.  42.  The  blocks  and  the  cobble  stones  that  the  city  authorities  may  declare  unfit  for  using 
again  will  be  broken  and  used  as  Macadam  on  streets  designated  by  the  city  ;  they  shall  be  con- 
structed as  follows : 

(a.)  The  ground  shall  be  well  graded,  giving  it  the  form  and  inclination  of  similar 
streets. 

(6.)  On  the  surface  thus  prepared  there  shall  be  laid  first,  gutters  of  cobble  stones  to  a  width 
of  from  2.5  to  3,3  feet.  These  shall  be  laid  as  specified  for  streets  paved  with  cobble  stones. 

(c.)  On  that  portion  of  the  ground  designed  for  the  roadway  there  shall  be  spread  a  bed 
of  broken  stone  of  6  to  8  inches,  reducing,  after  wetting  and  ramming,  to  4  to  6  inches  in 
depth. 

(d.)  On  this  strata  of  stone  there  shall  be  spread  a  bed  of  sand,  which  shall  be  well  wet  and 
rolled,  so  as  to  obtain  a  smooth  and  uniform  surface. 

ART.  49.  *  *  *  *  From  the  provisional  reception,  the  maintenance  of  the 
work  completed  will  be  performed  by  the  contractor  till  April  30th,  1880. 

ART.  50.  All  unexpected  degradations,  all  badly  executed  work,  not  only  during  the  progress 
of  construction,  but  also  during  the  years  of  maintenance,  will  be  repaired  by  the  contractor,  what- 
ever may  be  the  cause  of  the  degradation,  and  with  the  least  delay,  without  waiting  to  be  notified 


I  io  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

by  the  city,  under  penalty  of  a  fine  ot  50  francs  for  each  dny  of  delay  after  the  three  first  days- 
which  follow  that  of  the  discovery  of  the  degradation. 

Besides  that  penalty,  if  the  contractor  does  not  proceed  immediately  to  the  reparation  of  these 
unforeseen  accidents,  the  city  shall  have  the  authority  to  put  them  in  good  repair  in  his  place 
and  at  his  expense,  by  deducting  the  cost  from  the  estimate. 

AKT.  51.  On  April  1st,  1878,  the  city  will  make  a  new  and  minute  inspection  of  all  the  work 
done  during  the  five  seasons.  They  will  compare  the  state  of  the  work  done  with  that  of  each  of 
the  estimates  made  at  the  end  of  each  season,  and  if  it  be  found  that  the  works  are  in  compliance 
with  this  contract,  and  in  good  condition,  they  will  finally  accept  them  and  make  out  a  new  esti- 
mate, of  which  a  duly  certified  copy  will  be  furnished  the  contractor. 

ART.  52.  On  May  1st,  1880,  the  contractor  having  satisfied  the  first  part  of  the  obligations  de- 
volving upon  him  under  this  contract,  binds  himself  under  a  new  obligation  to  the  city,  that  of 
maintaining  for  a  period  of  fifteen  years,  from  May  1st,  1880,  to  April  30th,  1895,  the  works  exe- 
cuted, in  consideration  of  a  price  agreed  upon  in  advance. 

ART.  53.  The  maintenance  consists  in  repairs,  renewals  and  furnishing  materials  necessary  to 
the  sidewalks,  curbs,  gutters,  etc.;  in  doing  all  kinds  of  work  and  furnishing  materials  necessary 
to  at  all  times  maintain  the  surface  of  the  streets  and  sidewalks  paved  by  the  contractor,  in  a  per- 
fect state  of  uniformity. 

The  uniformity  of  the  surface  of  the  streets  and  sidewalks  shall  be  determined  by  the  use  of 
a  templet  of  iron  formed  to  the  normal  curve  adopted  for  the  surface  of  the  streets  and  sidewalks. 
This  templet,  applied  to  a  street  or  sidewalk,  must  not  present  at  any  point  a  swell  or  depression 
greater  than  0.4  inch . 

The  surface  of  the  streets  and  sidewalks  shall  not  show  any  cracks.  The  connections  with 
the  curbs  must  be  perfect. 

AKT.  54.  Whenever  the  curbs,  the  sidewalks,  the  roadways,  the  water  ways — in  a  word, 
everything  that  goes  to  make  a  part  of  the  street,  becomes  subject  to  a  displacement  or  derange- 
ment from  any  cause  whatever,  the  contractor  will  be  obliged  to  repair  them  immediately,  in  con- 
formity to  the  preceding  article.  Exception  is  made,  however,  to  all  that  applies  to  the  construc- 
tion or  repairs  of  water  or  gas  mains,  which  will  always  be  at  the  expense  of  the  respective 
grantees. 

ART.  55.  The  contractor  shall  proceed  at  once,  at  his  own  cost,  to  repair  any  degradation 
whatever,  without  notification  from  the  city. 

"Whenever  a  notification  from  the  city  becomes  necessary  to  warn  him  to  proceed  with  the  re_ 
paration,  the  contractor  will  be  liable  to  a  fine  of  ten  francs,  and  he  will  be  obliged  to  proceed 
with  the  reparation  within  24  hours  after  the  receipt  of  such  notification. 

If,  after  that  notice,  the  contractor  fails  to  proceed  with  the  repairs  of  the  degradation  indi- 
cated by  the  city,  the  latter  shall  proceed  with  the  work  ;  it  shall  make  the  reparation,  submit  the 
contractor  to  a  fine  of  fifty  francs,  and  retain  the  cost  of  the  reparation  and  fine  from  any  sums 
that  may  accrue  for  the  maintenance  of  the  streets,  and  in  case  that  should  not  be  sufficient,  from 
the  sureties. 

In  case  of  a  repetition  of  this  offense  occurring  during  the  course  of  a  single  year,  the  city,  be- 
sides the  right  which  it  always  reserves  to  make  the  reparation  on  the  account  of  the  contractor, 
in  conformity  with  the  preceding  paragraph,  will  impose  ou  the  contractor  a  fine  of  1,000 
francs. 

Finally,  on  a  third  infraction  in  the  course  of  the  same  year,  the  city  has  the  right  to  make 
besides  the  reparations  after  the  rules  established  above,  and  of  re-letting  the  work  of  maintenance 
to  another  at  the  cost  of  the  contractor ;  if  this  sale  results  in  a  loss  to  the  city,  it  shall  have  the 
right  to  reimburse  itself  from  the  sureties.  Incase,  on  the  contrary,  it  results  in  a  profit,  the 
contractor  shall  have  no  right  to  demand  it. 

ART.  59.  The  prices  for  the  works  executed  in  conformity  to  the  requirements  of  this  contract 
shall  be : 

(a.)  For  compressed  asphalte,  $5.88  per  square  yard. 

(&.)  For  sidewalk  asphalted,  $2.81  per  square  yard. 

(c.)  For  roadway,  with  gutters,  paved  with  sandstone  blocks  taken  from  streets  now  paved, 
$1.94  per  square  yard. 

(d.)  For  roadway  or  gutters  paved  with  new  sandstone  blocks  furnished  by  the  contractor, 
$8.41  per  square  yard. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS,  iir 

(e.)  For  roadway,  ihe  gutters  included,  paved  with  cobble  stones  taken  from  streets  now- 
paved  in  that  manner,  also  for  gutters  constructed  with  cobble  stones  on  Macadamized  streets, 
$1.02  per  square  yard. 

(f.)  For  roadway  paved  with  cobble  stones  furnished  by  the  contractor,  also  for  gutters  paved 
in  this  manner  on  streets  covered  with  compressed  a*phalte,  $1.91  per  square  yard. 

(g.)  For  Macadam  roadway,  $1.45  per  square  yard. 

(h.)  For  granite  curb  to  asphalted  sidewalks,  $0.95  per  lineal  foot. 

(i.)  For  sandstone  curb  to  asphalted  sidewalks,  $0.67  per  lineal  foot. 

(k.)  For  curb  cut  from  the  old  sandstone  s;abs  or  flags.  $0.39  per  lineal  foot. 

(I.)  For  granite  curb  used  in  the  edging  for  asphalte  of  streets,  $0  81  per  lineal  foot. 

ART  57.  The  price  for  maintaining  the  roadway  and  sidewalks  during  15  years  from  May  1st, 
1880,  to  April  80th,  1S95,  shall  be  calculated  from  the  total  area  constructed  by  the  contractor,  and 
shall  be  as  follows  : 

(a,)  For  maintaining  compressed  asphalte  streets  with  granite  curb,  $0.09  per  square  yard 
per  annum. 

(6.)  For  maintaining  asphalte  sidewalk,  whatever  the  kind  of  curb,  $0.04£  per  square  yard  per 
annum. 

(c.)  For  maintaining  roadway  or  gutter  paved  with  old  or  new  stone  blocks,  $0.29  per  square 
yard  per  annum. 

(d.)  For  maintaining  roadway  or  gutters  paved  with  cobble  stones,  $0.09  per  square  yard  per 
annum. 

(e.)  For  maintaining  Macadam,  including  the  sidewalks  and  curbs,  $0.15  per  square  yard  per 
annum. 

ART.  58.  Payment  for  work  done  will  be  made  to  the  contractor  in  the  following  manner: 

One-quarter  of  the  work  done  will  be  paid  for  in  cash,  the  remainder  in  City  bonds. 

The  bonds  will  have  15  years  to  run  ;  they  will  bear  interest  at  6  per  cent,  per  annum,  pay- 
able semi-annnally  ;  they  will  be  delivered  to  the  contractor  at  par. 

ART.  67.  The  sums  due  for  the  maintenance  of  streets  and  sidewalks  during  the  15  years 
which  follow  the  construction— from  May  1st,  1880,  to  April  30th,  1895— will  be  paid  by  the 
City  of  Jassy,  at  the  end  of  each  month,  after  deducting  all  that  the  contractor  owes  to  the  City 
for  repairs  made  in  his  name  and  at  his  expense,  and  fines.  These  payments  Avill  be  made  in  ci'j-h. 

ARTS.  69  to  71,  inclusive,  provide  that  the  contractor  shall  place  a  guaranty  of  100,000  francs 
in  bonds  of  Roumania,  which  may  be  replaced  by  bonds  of  the  City.  In  addition  10  per  cent,  of 
contract  price  shall  be  retained,  until  the  sum  of  400,000  francs  is  peached,  making  a  total  guaranty 
of  500,000  francs.  This  guaranty  shall  be  returned  to  him  as  follows:  May  1st,  1878,  250,000 
francs ;  and  at  the  end  of  the  years  ot  maintenance,  May  1st,  1895,  250,000  francs. 

ART.  72.  Six  months  before  the  expiration  of  the  fifteen  years  of  maintenance,  the  City 
authorities  will  make  a  general  -Inspection  of  all  the  work  done  and  maintained  and  make  an 
estimate  of  it. 

ART.  73.  If  during  this  inspection  the  City  discovers  the  necessity  of  any  repairs,  the  con- 
tractor shall  do  the  same  at  his  own  expense  during  the  following  six  months,  in  such  a  manner 
that  the  streets  maintained  by  him  shall  be  turned  over  to  the  City  in  a  good  condition  on  the 
day  the  contractor  completes  his  contract. 

Should  the  contractor  refuse  to  make  these  repairs,  the  city  shall  proceed  to  do  it  at  the  ex- 
pense of  his  warranty. 

ART.  74.  At  the  end  of  the  15  years  of  maintenance,  if  the  streets  are  in  a  good  condition, 
considering  only  the  effects  of  the  weather,  but  presenting  no  degradations,  the  final  acceptance 
of  the  works  will  be  made  and  the  guaranty  deposited  by  the  contractor  returned  to  him. 

The  coupons  of  bonds  deposited  as  guaranties  are  the  property  of  the  contractor,  who  will 
have  the  right  to  collect  the  sums  corresponding  to  each.  The  contractor  shall  also  have  the 
right  to  replace  the  bonds  deposited  by  him  as  guaranty  whenever  they  may  become  extinguished 
through  the  process  of  drawing  lots. 

ART.  89.  The  system  allowed  for  the  pavement  of  the  carriage  ways  is  that  of  compressed 
asphalte.  The  manufacture  of  this  compressed  asphalte  will  not  depart  from  the  rules  actually 
adopted  by  science  and  experience,  the  mode  of  execution  of  the  compressed  asphalte  remains  to 
be  agreed  upon  hereafter  between  the  City  and  the  contractor. 


112  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

APPENDIX  No.  5. 

Abstract  of  Specifications  and  Schedule  of  prices  for  the  construction  and  main- 
tenance of  foot-paths  and  sidewalks,  in  asphaltic  mastie,  and  the  Places  and 

roadways  in  compressed  asphalte  belonging  to  Municipal  service  of  Paris, 

from  January  1st,  1878,  to  December  31s 1. 1882.    Paul  Crochet,  Contractor. 

AKTICLE  1.  The  work  has  for  its  object — 1st.  The  maintenance  and  construction  of  foot 
paths  and  sidewalks  in  asphaltic  inastic,  situated  in  the  public  ways.  2d.  The  maintenance  and 
construction  of  compressed  asphalte  pavements.  3d.  The  new  works  ;  these  works  will  coin- 
prise  all  the  pavements  in  bitumen  and  asphalte. 

ART.  4. — The  present  letting  is  made  on  a  scale  of  prices,  and  the  amount  of  the  work  is 
completely  undefined,  so  that  the  contractor  cannot  make  any  demand  on  account  of  any  changes 
that  the  expenditure  may  be  subject  to. 

ART.  6.  When  the  adjoining  proprietors  or  other  parties  in  interest  have  to  bear  the  cost  of  the 
works  detailed  above,  or  to  contribute  in  any  proportion,  the  contractor  will  be  held  to  execute 
the  work  at  the  same  price  as  that  done  at  the  cost  of  the  City  of  Paris,  and  conformably  to  the 
orders  of  the  Engineers. 

ART.  7.  Foot  pavements  shall  have  the  widths  determined  by  the  administration,  they  shall  be 
composed  of  pavement  in  mastic  supported  on  the  side  of  a  public  road  by  a  curb  the  height  of 
which  shall  commonly  be  of  6J  to  4  inches. 

ART.  9.  The  ordinary  curbs  in  granite  shall  be  llf  inches  wide  on  top  with  a  total  fall  across 
off  inch  ;  13  inches  wide  at  the  base,  which  shall  be  horizontal ;  llf  inches  high  on  the  front  face, 
which  shall  have  a  batter  of  H  inches. 

ART.  16.  The  mastic  pavements  will  be  formed  of  a  layer  of  pure  asphaltic  mastic  at  least  T9B 
inch  thick,  resting  on  a  bed  of  hydraulic  concrete  4  inches  thick  which  comprises  a  covering  of 
hydraulic  mortar  at  least  $  inch  thick. 

ART.  17.  The  compressed  asphalte  pavements  will  consist  of  an  upper  layer  of  compressed 
asphalte  1-J-  to  2£  inches  thick,  resting  on  a  foundation  of  hydraulic  lime  or  cement,  concrete  4  to 
6  inches  thick  covered  as  above  with  mortar  or  upon  an  old  Macadam  roadway  picked  over  and 
covered  with  a  thin  coat  of  hydraulic  mortar. 

ART.  21.  The  asphaltic  mastic  employed  either  for  new  or  repairing  old  paving  shall  be  com- 
posed of  naturally  impregnated  rock  with  natural  bitumen  of  good  quality,  coming  exclusively 
from  mineral  rocks. 

The  fictitious  bitumens  extracted  by  the  purification  of  the  heavy  oils  of  schists,  the  distilla- 
tion of  coal,  thofce  so-called  fatty  bitumens  and  all  other  analogous  products  shall  be  rigorously 
proscribed. 

The  rock  employed  after  being  reduced  to  powder  will  be  melted  with  a  sufficient  quantity  of 
purified  natural  bitumen  to  form  a  mastic  which,  when  cold,  presents  a  homologous  mass  slightly 
elastic,  and  which  does  not  soften  under  a  hot  sun.  This  mastic  shall  be  moulded  into  blocks. 
There  may  also  be  used  blocks  of  bituminous  mastic  with  a  base  of  slates  manufactured  by  the 
process  of  M.  Sebille. 

ART.  22.  The  contractor  shall  be  bound  to  employ  under  the  orders  of  the  Engineer  upon 
each  public  way  the  bituminous  mastic  above  described. 

The  mastic  shall  be  formed  of  a  mixture  of  natural  bitumen,  in  the  proportion  of  one-twelfth 
of  its  weight  at  most,  and  the  calcareous  asphalte  rocks  of  Seyssel,  Seyssel-Forens,  Pyrimont  or 
Volants,  of  Val  de  Travers  or  Lobsan,  or  others  deemed  equivalents  by  the  Engineers. 

The  mastic,  having  a  bas«  of  slate  of  M.  Sebille,  will  be  formed  of  a  mixture  of  bitumen 
described  in  Art.  23,  following,  and  of  powdered  red  or  blue  slate  of  Ardennes,  powdered  chalk  of 
Mendon  or  of  Nanterre  and  of  silica  from  the  basin  of  Paris,  in  the  following  proportions,  by 
weight : 

Refined  mineral  bitumen 30 

Ground  slate 35 

Powdered  chalk 10 

Silica,  ground  and  sifted 25 

100 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  113 

ART.  23.  Ihe  bitumen  shall  come  as  much  as  possible  from  the  washings  of  bituminous 
sandstone  or  the  asphaltic  rock  of  Maestu,  and  in  their  default,  from  the  dry  pitch  of  Trinidad, 
perfectly  puiified.  It  ought  to  be  viscid  at  the  ordinary  temperature ;  never  brittle  or  liquid ; 
drawn  into  threads  it  should  lengthen  and  only  break  in  very  fine  points. 

ART.  24.  The  rock  employed  should  be  calcareous,  soft,  with  fine  grain,  texture  fairly  com- 
pact, regularly  impregnated  with  bitumen  so  as  not  to  show  black  and  white  spots  ;  it  should  be 
of  a  brown  color  ;  heated  to  122  to  140°  F.  it  should  soften  and  break  on  being  torn.  Care  must 
be  '  aken  for  the  areas  in  asphalte  to  choose  only  such  pieces  as  are  of  the  most  even  grain  and 
richest  impregnation.  The  rock  of  Lobsan,  however,  should  not  be  employed  alone  in  the 
asphalte  roadways,  it  ought  to  be  mixed  with  other  rocks  less  fat  in  proportions,  which  will  be  de- 
termined by  the  Engineers  according  to  the  composition  of  the  other  rocks.  It  should  contain 
at  least  7  per  cent,  of  bitumen,  and  at  the  most  93  per  cent,  of  lime;  its  change  into  mastic 
must  not  require  more  than  9  per  cent,  of  bitumen. 

ART.  25.  The  materials  entering  into  the  composition  of  the  pavements  are  the  mastics 
described  in  Art.  22,  pure  gravel  grit  and  natural  bitumen  to  assist  the  melting.  These  materials 
ought  to  be  generally  employed  in  the  following  proportions,  by  weight: 

(  Asphaltic  mastic 100 

Foot  pavements  with  abase  of  asphalte..  •<  Bitumen  6 


(  Asphaltic  mastic 100 

......  ~\ 


Foot  pavements  with  a  base  of  slate <  Bitumen 7 

(Gravel 60 

ART.  26.  One  month  before  the  award  of  this  contract  the  competitors  must  deposit  at  the 
office  of  the  works  in  Paris,  samples  of— 1st,  A  block  of  the  mastic  described  above;  2d,  Speci- 
mens of  the  asphaltic  rocks  and  the  natural  bitumens  they  intend  to  use;  8d,  A  note  indicating 
the  elements  of  the  composition  of  the  mastics  and  proportions  of  the  various  rocks  that  they 
intend  to  employ  in  the  composition  of  the  asphaltic  areas. 

The  blocks  and  specimens  of  rocks  and  bitumen  to  have  the  trade-marks  of  the  works  from 
whence  they  came  and  the  signatures  of  the  competitors. 

The  necessary  certificates  to  compete  for  the  contract  will  not  be  delivered  till  after  the 
examination  and  acceptance  by  the  Engineers  of  the  specimens  deposited.  During  all  the 
term  of  this  contract  the  contractor  can  only  use  materials  exactly  similar  to  the  specimens  de- 
posited. 

ART.  27.  Provides  for  continuous  inspection  of  the  contractor's  works  or  the  right  to  compel 
the  contractor  to  manufacture  the  mastic  in  the  depots  belonging  to  the  city. 

ART.  81.  The  lime  employed  is  to  be  hydraulic  lime  in  powder.  It  must  be  brought  onto  the 
works  in  sealed  bags,  marked  with  the  name  of  the  maker.  Only  the  lime  and  cement  designated 
in  the  specifications  for  the  construction  and  repair  of  sewers  will  be  allowed. 

A3T.  32.  The  broken  flint  must  pass  through  a  ring  of  2^  inches  and  be  at  least  f-inch  thick. 
It  must  be  free  from  earthy  matters  and  washed  clean. 

ART.  33.  The  sand  shall  be  dredged  from  the  Seine  and  well  cleansed  from  all  foreign  matter; 
it  shall  be  screened  from  all  grains  larger  than  $•  inch  for  the  mortars,  or  £,  inch  for  grit 
for  the  mastic  pavements;  the  grit  for  this  last  purpose  shall  be  perfectly  washed  and  dried  before 
use. 

ART.  34.  The  mortar  of  hydraulic  lime  shall  be  composed  of  5  parts  of  sand  and  2  parts  of 
lime,  by  volume,  furnished  in  powde»;  the  mixture  shall  be  directly  reduced  to  a  paste  by  adding 
the  quantity  of  water  exactly  required  to  reduce  it  to  the  consistency  of  plastic  clay. 

The  cement  mortar  shall  be  composed  of  one  part  of  hydraulic  cement  of  Bourgogne  or  Port- 
land cement  of  Boulogne  and  3  parts  of  sand;  the  sand  and  cement  shall  be  thoroughly  mixed 
before  the  addition  of  any  waten.  All  mortar  which  shall  have  set  shall  be  rejected. 

ART.  35.  The  beton  shall  be  composed,  ordinarily,  of  two  parts  in  volume  of  mortar  and  three 
of  stone.  The  mixture,  made  either  by  the  rake  or  cylinder,  must  be  perfectly  uniform. 

All  beton  not  used  at  the  time  of  making  shall  be  rejected. 

ART.  36.  The  bed  of  beton  for  the  foundation  of  the  sidewalks  shall  be  well  rammed  and  com- 
pressed, and  must  at  least  commence  to  set  and  dry  before  receiving  mastic  or  asphalte.  The 
beton  shall,  in  addition,  be  covered  with  a  layer  of  mortar  £  inch  thick. 


114  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

The  gravel  for  foundation  shall  pass  in  every  direction  through  a  ring  2  inches  in  diameter. 
It  must  be  perfectly  compressed  and  sprinkled  withlime  grout.  This  foundation  shall  have  com- 
menced to  set  before  the  application  of  the  mastic,  and  shall  be  covered  with  a  layer  of  mortar 
like  the  beton. 

ART.  89.  The  ground  upon  which  the  mastic  pavement  is  to  b^  placed  shall  always  be  pre- 
viously rammed,  watered,  and  crowned  with  care.  When  it  is  thus  made  solid  the  contractor 
shall  spread  over  it  the  foundation  layer,  formed  according  to  the  orders  of  the  Engineer,  either  a 
bed  of  beton  or  of  sand  covered  by  a  byer  of  mortar,  or  a  bed  of  sand  impregnated  with  goudron 
2|  inches  thick,  or  any  other  foundation  prescribed  by  the  Engineer. 

In  all  cases  the  pavement  shall  not  be  laid  till  the  foundation  has  attained  the  firmness 
desired,  and  become  quite  dry. 

The  contractor  must  conform  to  the  following  orders  for  the  manufacture  of  the  mastic  to  be 
used  for  pavements. 

The  mastic  bhall  be  prepared  and  cast  in  one  or  more  manufactories  ^belonging  to  the  con- 
tractor, and  which  shall  always  remain  open  to  the  inspection  of  the  engineers  and  their  agents. 

The  contractor  shall,  besides,  establish  in  the  manufacturing  depots,  both  of  asphalte  and 
mastic,  offices  exclusively  for  the  agents  of  the  administration  set  apart  for  the  inspection  of  the 
composition  of  these  materials.  These  materials  shall  not  be  admitted  into  the  works  without  a 
carter's  delivery  note  given  by  the  inspector,  setting  forth  that  they  have  been  manufactured  in 
accordance  with  the  specifications. 

There  shall  only  be  allowed  in  the  works  blocks  of  mastic  conforming  to  the  samples  de- 
posited and  accepted  before  the  award,  and  bearing  their  trade-mark,  or  the  old  mastics  from  the 
walks  and  streets  of  Paris.  All  other  bituminous  matters,  resinous  or  fatty,  found  in  the  works 
by  the  agents  of  the  administiation  will  subject  the  contractor  to  a  deduction  of  $100  for  each 
time. 

To  assure  the  execution  of  these  conditions  the  contractor  must  not  have  in  any  manufactory, 
under  the  same  penalty,  any  other  blocks  than  those  which  should  be  prepared  in  his  works,  and 
the  old  mastics  taken  up. 

The  use  of  the  old  mastic  is  authorized  in  the  works  of  the  city  in  the  proportion  of  one-half 
with  the  new.  The  pieces  of  the  old  sidewalks  having  been  perfectly  cleaned  with  great  care, 
and  regenerated  by  the  addition  of  new  purified  bitumen  and  a  sufficient  quantity  of  powdered 
asphalte  to  render  the  old  mastic,  when  melted,  of  the  aspect  and  consistence  of  the  blocks  in 
fusion. 

This  mastic  shall  be  melted  in  hermetically  closed  boilers,  on  wheels  of  a  model  approved  by 
the  administration,  and  arranged  so  that  the  material  can  be  conveyed  from  the  factory  to  the 
place  to  be  used,  ready  to  be  employed. 

For  melting,  the  mastic  is  broken  into  pieces  4  inches  cube,  then  the  bitumen  is  melted  and 
the  mastic  added  little  by  little. 

The  grit  must  not  be  thrown  into  the  boiler  till  the  mastic  is  completely  dissolved. 
During  the  whole  time  of  the  operation  the  matter  must  be  stirred  up  almost  constantly,  so 
that  the  combination  shall  be  well  made  and  the  mastic  not  burned. 

The  mastic  being  well  melted  and  perfectly  homogeneous,  it  shall  be  run  out  in  bands  of 
about  5  feet  wide,  spread  with  a  wooden  float,  and  leveled  with  a  strike,  so  as  to  present  neither 
fissure  nor  joint.  The  mastic  must  be  perfectly  level,  and  match  exactly  with  the  curbs,  &c., 
against  which  it  is  laid.  For  this  purpose  the  parts  of  the  curbs,  flags,  &c.,  which  will  be  in  con- 
tact with  the  bitumen  shall  be  previously  warmed  and  goudroned. 

ART.  40.  Upon  the  Boil,  well  shaped  and  rammed,  shall  be  placed  a  bed  of  concrete,  covered 
with  a  layer  of  mortar. 

The  asphaltic  rock,  conforming  to  Article  24,  broken  down  or  decrepitated  by  heat,  shall  be 
raised  to  a  uniform  temperature  of  from  248°  to  266°  F.,  and  carried  to  the  place  of  employment 
in  vehicles  that  will  prevent  as  much  as  possible  the  loss  of  heat.  It  must  be  completely  freed 
from  the  water  it  contains.  The  use  of  old  compressed,  taken  from  old  roads,  is  authorized  for 
mixture  with  new  asphalte,  in  the  proportion  of  one  quarter  of  old  compressed  to  three-quarters 
of  new  rock,  provided  that  the  old  shall  be  cleansed  with  great  care  before  grinding  and  mixing 
with  the  new. 

Asphalte  shall  not  be  put  on  the  concrete  foundation  until  it  Is  peerfectly  set  and  dry. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    115 

The  powder  shall  be  spread  with  a  thickness  about  two-fifths  more  than  the  finished  thick- 
ness, leveled  with  great  care,  shall  be  rammed  at  first  carefully,  then  gradually  augmenting  the 
force  by  means  of  cast-iron  pilons,  heated  to  the  proper  temperature  in  portable  furnaces.  In 
specially  exceptional  cases,  the  compression  may  also,  with  the  written  permission  of  the  Engineer 
be  accomplished  by  means  of  rollers. 

In  every  case,  after  the  pilonnagc  is  finished,  the  surface  shall  be  smoothed  by  means  of  & 
heat  -d  iron  ( lissoir). 

The  road  shall  not  be  open  to  traffic  until  it  is  quite  cool. 

ART.  41.  The  specifications  referring  to  the  construction  of  roads  and  footpaths  are  applicable 
to  the  maintenance  of  the  same.  The  contractor  will  be  entitled  to  the  old  material,  and  will 
make  the  repairs  in  new  material  or  in  the  mixture  specified  in  Articles  89  and  40. 

ART.  43.  In  conformity  with  the  contract  price,  stipulated  hereafter,  diminished  by  the 
rebate  of  the  awarded  contract,  the  contractor  must  make  the  necessary  repairs  to  all  asphaltic 
mastic  footpaths  and  aress,  furnishing  the  necessary  labor  and  materials,  so  that  they  shall  be 
kept  in  a  proper  state.  He  must  each  year  of  the  duration  of  the  contract  completely  relay,  in 
new  material,  at  least  the  fifteenth  part  of  the  surfaces  of  mastic  and  compressed  asphalte.  The 
surlaces  in  mastic  must  be  properly  plane  and  regular,  presenting  neither  hollows  nor  projections 
of  more  than  three-eighths  of  an  inch  in  a  circle  whose  radius  is  3£  feet.  These  surfaces  must  be 
free  from  fissures. 

ART.  45.  As  the  works  in  asphalte  or  mastic  are  received  by  the  engineers  they  will  pass  into 
the  charge  of  the  contractor  who  will  receive  for  the  maintenance  the  price  stipulated,  commenc- 
ing from  the  1st  of  January  next  following  their  acceptance,  whatever  may  be  the  date  of  said 
acceptance. 

ART.  46.  The  contract  prices  diminished  by  the  rebate  of  the  award  are  applicable  to  the  entire 
surface  occupied  by  footpaths  or  compressed  asphalte,  whatever  may  be  their  condition. 

In  the  nine  last  months  of  the  year  installments  may  be  paid  on  the  contract  when  the  engi- 
neers recognize  that  the  conditions  have  been  loyally  carried  out.  The  accumulated  sums  of  these 
installments  must  not  exceed  four-fifths  of  the  amount  of  the  sums  which  shall  be  due  after  the 
time  has  expired.  The  balance  of  the  contract  price  of  the  year  will  be  paid  in  the  course  of  the 
first  quarter  of  the  following  year. 

ART.  47.  The  repairs  over  trenches  for  sewers,  water  and  gas-pipes,  or  other  works,  will  be 
paid  for  once  at  the  schedule  price,  but  no  demand  for  further  payments  on  account  of  sinkings 
or  other  dilapidations  will  be  entertained,  and  the  surfaces  on  these  trenehes  must  be  kept  in  the 
same  good  condition  as  the  others.  For  the  purpose  of  securing  settlement,  the  contractor  may 
keep  the  trenches  repaired  with  flint  (Macadam)  not  longer  than  15  diys. 

ART.  49.  All  damages  in  the  bituminous  surface,  such  as  fissures  or  cracks  of  at  least  ^  inch 
in  width,  or  parting  from  the  curbs  T3S  inch  in  width,  any  lifting  up  or  breaking  away  of  the 
mastic  for  at  least  ,3B  in  depth,  depression  in  consequence  of  settlement  off  inch  at  least  in  depth 
under  the  straight  edge,  3J  feet  long,  will  subject  the  contractor  to  a  deduction  of  3  francs  (58 
cents)  per  day,  when  the  repairs  shall  not  have  been  done  within  48  hours  after  notice  given  by 
the  Engineer. 

ART.  51.  During  the  continuance  of  frost,  and  during  the  first  month  after  the  commence- 
ment of  the  thaw,  there  shall  be  no  repairs  to  the  pavements  maintained  by  the  contractor,  and 
the  inspection  for  defects  shall  be  suspended,  but  the  contractor  shall  fill  with  sand  and  gravel  any 
holes  in  these  pavements  within  24  hours  after  notification  by  the  Engineer,  under  a  penalty  of  10 
francs  ($1.93)  for  each  day  they  remain  unfilled.  He  may  be  luthorized,  in  exceptional  cases,  to 
fill  the  holes  with  broken  flint  or  melted  bitumen,  but  must  replace  the  flint  or  bitumen  with 
asr>halte  as  soon  as  the  weather  permits.  It  must  be  so  arranged  that  the  main  repairs,  intended 
to  re-establish  the  normal  outline  of  the  roadways,  are  effected  from  May  1st  to  November  1st. 

ART.  57.  The  contractor  shall  execute  in  private  houses  the  junctions  rendered  necessary  by 
changes  in  the  public  way,  which  will  be  paid  for  according  to  the  price  of  his  contract,  subject  to* 
the  rebate  when  the  works  are  executed  on  account  of  the  city. 

ART.  65.  When  a  workman  leaves  one  of  the  districts  of  the  works  under  the  Municipal  ser- 
vice, he  must  have  a  certificate  from  the  contractor  showing  the  cause  for  which  he  left. 

This  certificate  shall  be  submitted  at  once  to  the  Engineer,  who  shall  be  at  liberty  to  refuse 
the  right  of  employing  the  said  workman,  without  the  contractor  deriving  therefrom  any  excuse 


i*6    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

for  not  furnishing,  when  requisite,  the  number  of  workmen  required.    In  default  of  a  certificate, 
the  workman  cannot  be  admitted,  except  on  the  written  order  of  the  Engineer. 

NOTE. — There  are  75  articles  in  this  contract,  those  not  given  referring  to  the  setting  of  curbs, 
etc.,  transport  of  materials,  and  the  relations  between  the  Engineer  and  contractor. 


SCHEDULE    OF    THE    PRICES   FOR   THE   WORK   SPECIFIED 

ABOVE. 


NOTE.  —All  the  prices  below  comprise  the  incidental  expenses  and  the  profits  of  the  contractor 
and  are  subject  to  the  rebate  of  the  award. 

(This  contract  is  let  in  three  lots,  the  rebates  are  7£,  20.2£,  and  14#,  respectively.) 

DAY  WORK.— The  day  of  a  workman,  cart  or  machine  shall  be  ten  hours  of  effective  work  in 
all  seasons  ;  fractions  more  or  less  shall  be  counted  by  the  hour,  or  fa  of  the  day. 

The  night  hours  shall  be  paid  half  as  much  more  as  those  of  the  day,  excepting  watchmen. 
Night  hours  will  be  counted  only  from  7  P.  M.  to  5  A.  M.  in  summer,  and  from  5  p.  M.  to  7  A.  M.  in 
winter.  The  summer  period  begins  March  1st,  and  winter  November  1st. 

1.  A  day  of  a  laborer 96* 

2.  "        an  ordinary  mason ...    1.06 

8.         "        an  asphalte  helper,  or  of  a  mason's  or  paver's  helper 87 

4.  "        granite  cutter 1.86 

5.  "        sandstone  cutters,  pavers  and  asphalte  workers 1.26} 

6.  "        watchman 53 

7.  Night  watchman 79 

8.  Day  of  one-horse  wagon  and  driver 2.70 

9.  •'      two-horse      "  "      4.05 

21.  1  cubic  yard  of  utone  broken  for  concrete 1.22 

22.  "  ground  hydraulic  cement 513 

28.  "  river  sand 1.18 

24.  pit  sand 89 

25.  "  river  sand,  washed  and  dried  for  mastic 1.48 

27.  100  pounds  of  Roman  cement 58 

28.  "  Portland  cement 67 

29.  asphaltic  rock 68 

$0.  "  mineral  goudron,  from  Lobsang,    Bastennes,  or  other  recognized  as 

equivalent  to  them,  and  purified  Trinidad  or  Maestu..     3.24 

49.  1  cubic  yard  of  mortar,  composed  of  two   parts  of  ground  hydraulic  lime  and  five 

parts  of  sand 3.10 

50.  1  cubic  yard  of  mortar,  composed  of  one  part  of  hydraulic  cement  of  Bourgoyne 

and  three  parts  of  sand 5.02 

51.  1  cubic  yard  of  mortar,  composed  of  one  part  of  Portland  cement  and  three  parts  of 

sand 6.42 

52.  1  cubic  yard  of  concrete,  composed  of  three  parts  of  broken  stone  and  two  parts  of 

mortar  (No.  49) 8.03 

53.  1  cubic  yard  of  concrete,  composed  of  three  parts  of  stone  and  two  parts  of  mortar 

(No.50) 3.99 

54.  1  cubic  yard  of  concrete,  with  mortar  (No.  51) • 4.65 

55.  100  pounds  of  natural  bituminous  mastic  in  blocks,   made  from  rock  of  Seyssel,  or 

other  equivalent,  ready  to  be  employed 1.02 

60.  100  pounds  of  compressed  asphalte,  taken  from  streets  to  be  repaired,  shall  be  taken 

by  the  contractor  (without  rebate)  at 35 

61.  1  square  yard  of  old  sidewalks  in  mastic  shall  be  taken  by  the  contractor,  without 

regard  to  its  thickness  and  without  rebate,  at 19 

70.  Taking  up  1  square  yard  of  compressed  asphalte,  piling  the  material  included. 014 

71.  Taking  up  1  square  yard  of  mastic  sidewalk,  with  piling  the  material 003 

^8.  Cleaning  and  leveling  an  old  Macadam  road  to  secure  a  surface  of  mortar  for  com- 
pressed asphalte,  per  square  yard  • 10 

83.  1  square  yard  of  new  natural  asphaltic  mastic.  0 . 6  inch  thick 53 

94.  Greater  or  less  value  of  each  j^5  of  an  inch  in  thickness 045 

95.  1  square  yard  of  sidewalk  relaid  in  natural  asphaltic  mastic,  0.6  inch  thick,  the  old 

material  belonging  to  contractor 40 

96.  Greater  or  less  value  of  each  T$ff  inch  in  thickness 025 

97.  1  square  yard  of  pavement,  0.6  inch  thick,  composed  of  one-half  new  and  one-half 

new  and  one-hilf  old  mastic 50 

cements  composed  as  above 32 

more  or  less.. .  02 


J.  1  square  yard  of  repairs  of  pa\ 
J.  For  each  T§0  in  thickness,  mor< 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    117 

102.  1  square  yard  of  compressed  asphalte,   1.6  inches  thick,  comprising  regulating  the 

surface  of  the  ground,  hut  neither  excavation,  embankment  iior  foundation  of  con- 
crete   173 

103.  For  each  T$0  in  thickness,  more  or  less IT 

105.  1  square  yard  repairs  of  road  1.6  inches  thick,  the  contractor  retaining  the  old  ma- 

terial    1.04 

106.  For  each  T$w  in  thickness,  more  or  less 17 

108.  1  square  yard  of  foundation    for  pavement  iti  asphalte  or  mastic,  comprising  regulat- 

ing and  ramming  the  roadbed,  but  not  excavation. 

109.  1  square  yard  concrete  of  hydraulic  cement  rammed  to  4  inches]  in  thickness,  com- 

prising a  covering  of  mortar,  No.  49,  at  least  T$5  inch  thick 84 

110.  1  square  yard  concrete  of  cement,   No.   53,  rammed  to  4  inches  thick,  comprising  a 

covering  of  mortar,  No.  50 4& 

111.  1  square  yard  concrete  of  cement,  No.   54,  rammed  4  inches  thick,  covered  with 

mortar  No.  51 64 

112.  1  square  yard  on  natural  soil,  with  a  bed  of  sand  0.8  inch  thick 04 

117.  Repairs  in  which  all  or  a  part  of  the  old  materials  are  used,  will  be  paid  for  at  three- 
quarters  of  the  prices  above  mentioned. 

207.  1  square  yard  of  sidewalk,  in  natural  mastfc,  half  an  inch  thick,  comprising  a  hydraulic 

lime  concrete  foundation,  4  inches  thick  after  ramming,  with  regulating  but  not  ex- 
cavatiner 98 

208.  Note.    When  the  foundation  is  in  cement  concrete  the  price  above  will  be  increased 

by  the  respective  diflerences  between  each  of  the  prices  of  Nos.  110  and  111,  and 
that  of  109. 

209.  1  square  yard  of  mastic  like  207,  on  the  natural  ground,  covered  with  abed  of  sand  0.8 

inch  thick     68 

210.  1  square  yard  of  mastic  like  207,  on  the  natural  ground,  covered  with  hydraulic  mor- 

tar  68 

211.  Note.    When  the  pavement  is  one-half  new  mastic  with  old  material,  the  prices  above 

will  be  dimished  by 09 

212.  1  square  yard  of  compressed  asphalte  1.6  inches  thick,   including  a  foundation  of  hy- 

draulic lime  concrete,  rammed  4  inches  thick,  including  dressing  and  ramming  the 

soil  but  not  excavation 2.07 

213.  1  square  yard  of  compressed,  with  concrete  of  cement  No.  51 2.21 

Additional  price  for  work  executed  on  embankments  more  than  1  yard  high,  or  on 

trenches,  whatever  may  be  the  thickness  of  the  pavement  or  concrete. 

215.  1  square  yard  of  mastic  $2 

216.  "        «'        compressed 86 

217.  Maintenance  of  1  square  yard  of  sidewalk  In  asphaltic  mastic,  in  conformity  with  these 

specifications,  per  annum 0& 

218.  The  same  for  roads  in  compressed  asphalte 19 

219.  Additional  price  for  maintaining  cross-walks  of  compressed  asphalte  on  Macadamized 

roads,  and  of  gutters  bordering  them 10 

248.  For  works  not  mentioned  in  the  present  schedule,  the  prices  in  the  schedules  now  in 
forcefor  maintenance  of  public  ways  or  sewers  ami  water  service  will  be  paid: 
which  prices  will  be  subject  to  the  rebate  of  the  present  letting. 


DISCUSSION    ON 

THE  CONSTRUCTION  AND  MAINTENANCE  OF 

ROADS. 


By  ARTHUR  SPIELMAN  and  CHARLES  B.  BRUSH,  GEORGE  D.  ANSLEY, 
A.  B.  HILL,  CHARLES  DOUGLAS  Fox,  E.  LAVOINNE,  E.  B.  VAN 
WINKLE,  B.  F.  MORSE,  E.  S.  CHESBROUGH,  E.  R.  AN- 
DREWS, C.    SHALER   SMITH,  M.  MERRIWETHER, 

J.  E.  HlLGARD,  D.  E.  MCCOMB,  F.  RlNECKER, 

J.  J.  R.  CROES,  JOHN  BOGART,  C.  C. 
MARTIN  AND  EDWARD  P.  NORTH. 


A.  SPIELMAN  AND  CHARLES  B.  BRUSH  (SPIELMAN  &  BRUSH). — 
Some  of  the  views  expressed  in  Mr.  North's  paper  on  "  the  construction 
and  maintenance  of  roads,"  being  at  variance  with  the  results  of  the  ex- 
perience of  our  firm,  in  the  building  of  36,000  square  yards  of  Telford  roads 
in  1875  and  1876,  and  about  25,000  square  yards  in  1878  and  1879,  part  of 
this  latter  amount  being  now  in  the  course  of  construction,  we  herewith 
submit  the  principal  facts  in  relation  to  these  roads,  and  our  conclusions 
therefrom. 

The  roads  are  80  feet  wide  between  house  lines,  and  are  located  in  the 
northern  part  of  Hudson  County,  New  Jersey  ;  they  are  built  exclusively  of 
trap  rock,  obtained  from  and  along  the  line  of  the  road,  the  stone  for  the 
upper  courses  having  been  broken  by  a  stone  crusher  erected  on  the  road 
by  the  contractor,  the  average  haul  from  the  crusher  not  exceeding  2,000 
feet.  No  binding  except  the  screenings  and  detritus  of  the  stone  was  al- 
lowed in  the  work,  and  in  each  case  the  foundation  is  of  rubble,  8  inches 
deep,  and  the  superstructure  of  broken  stone,  4  inches  thick,  when  com- 
pacted. 

The  roads  built  under  our  direction  in  1875-1876  may  be  divided  into 
two  classes  : 

1.  Roads  by  the  side  of  horse  railroad  tracks. 

2.  Roads  free  from  horse  railroad  tracks. 


120    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

In  the  first  case  the  width  of  the  roadway  from  curb  to  curb  is  55  feet, 
which  includes  18  feet  of  trap  block  pavement  for  the  tracks,  and  5  feet  for 
the  gutter. 

In  the  second  case  the  width  between  the  curbs  is  40  feet,  including  5 
feet  of  block  pavement  for  the  gutter. 

In  both  cases  the  8-inch  foundation  was  first  carefully  laid,  and  great 
care  taken  to  allow  for  perfect  sub-drainage.  Cess-pools,  filled  in  with 
broken  stone,  were  built  at  intervals  of  about  200  feet  on  both  sides  of  the 
road,  which  collect  all  the  water  that  accumulates  in  the  foundation  of  the 
pavement,  and  these  cess-pools  are  drained  by  6-inch  stoneware  pipes  into 
adjoining  receiving  basins. 

A  particular  illustration  of  the  importance  of  this  sub-drainage  came 
under  our  notice.  In  December,  1875,  just  after  considerable  of  the  foun- 
dation had  been  laid,  legal  difficulties  arose,  the  work  was  suddenly 
stopped,  and  remained  in  this  unfinished  condition  until  the  spring  of  1876. 
receiving  in  the  meantime  the  wash  from  the  adjoining  hill-sides.  When 
the  work  was  recommenced  the  interstices  between  the  foundation  stones 
of  the  pavement  in  many  places  were  filled  in  with  earth.  After  unsuccess- 
fully attempting  to  remove  this  earth,  the  foundation  at  these  points,  as 
far  as  they  could  be  ascertained,  was  taken  up  and  relaid  :  but  as  soon  as 
the  superstructure  of  the  road  was  completed  we  found  that,  in  certain 
spots,  it  was  always  wet,  and  the  surface  of  the  road  was  continually 
broken.  These  spots  invariably  indicated  the  points  where  the  foundation 
was  clogged,  and  the  difficulty  was  only  effectually  remedied  by  relaying 
the  foundation,  or  by  building  blind  drains  which  carry  off  the  accumulat- 
ing water. 

On  the  top  of  the  foundation  thus  prepared,  2-inch  stone  was  then  put 
on,  sprinkled,  and  rolled  wiih  a  horse  roller  of  150  pounds  per  inch  run. 
The  one-inch  stone  and  screenings  were  then  spread,  sprinkled,  and  rolled 
with  a  steam  roller  of  about  400  pounds  per  inch  run. 

After  the  rolling  was  partially  completed  the  passing  traffic  was  allowed 
upon  it,  and  any  large  stones  that  came  to  the  surface,  as  well  as  all 
small  stones  that  failed  to  bind,  were  raked  off  and  sent  back  to  the 
crusher  to  be  re-broken  for  screenings.  No  water-worn  or  other  rounded 
stones  were  allowed  in  the  work.  Advantage  was  taken  of  every  rainfall 
to  roll  the  surface  of  the  road,  because  we  found  that  it  could  be  com- 
pacted much  more  thoroughly  in  wet  than  in  dry  weather.  Where  the 
pavement  was  laid  in  a  soft  substratum  it  required  nearly  double  the 
amount  of  rolling  sufficient  for  a  solid  foundation. 

The  grades  of  these  roads  vary  from  6%  feet  to  8  inches  per  100  feet 
and  the  crowns  vary  from  1 2  inches  to  8  inches. 

The  roads  have  now  been  open  for  traffic  about  three  years ;  those 
along  the  railroad  tracks  are  used  by  about  600  wagons  per  day,  the 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    121 


others  by  about  400  wagons  per  day.  Fully  one  half  of  the  traffic  on  both 
roads  consists  of  heavy  beer  wagons  from  the  adjoining  breweries,  stone 
trucks  and  ice  carts,  ranging  in  weight  from  3  to  6  tons ;  the  balance  of 
the  traffic,  of  ordinary  farm  wagons,  carriages,  etc. 

No  especial  care  has  been  taken  of  the  roads,  except  to  see  that  the 
gutters  and  culverts  are  kept  clean.  No  ruts  have  ever  appeared,  and  the 
surface  is  now  smooth  and  in  good  condition.  In  hot  weather  the  roads 
are  somewhat  dusty,  and  in  long  dry  spells  they  will  loosen  and  break  up 
in  spots,  where  disturbed  by  the  corked  shoes  of  horses  drawing  very 
heavy  loads,  but  after  the  first  rain  the  surface  immediately  rebinds  and 
again  becomes  perfectly  smooth. 

Wind  and  water  are,  perhaps,  the  two  greatest  enemies  of  Macadam 
roads ;  the  wind,  by  blowing  off  the  slight  dust  which  naturally  accumulates 
on  the  surface,  removes  from  the  road  the  cushion,  which  is  not  only  a 
relief  to  the  traveler,  but  which  also  preserves  the  metal  of  the  road  from 
a  vast  amount  of  wear  and  tear;  the  water,  by  flooding  the  road,  has 
sometimes  the  same  effect  as  the  wind,  and  if  by  any  means  the  surface 
of  the  road  is  exposed  to  a  running  stream  the  stones  are  sure  to  loosen. 

The  only  effectual  remedy  we  found  was  to  rarse  the  crown  of  the  road 
sufficiently  to  shed  the  water  quickly  into  the  gutters,  and  to  keep  the 
road  sprinkled,  so  that  when  the  winds  and  floods  came  the  surface  would 
be  smooth  and  compact  and  not  liable  to  their  disintegrating  influences. 

On  the  roads  by  the  side  of  the  horse  railroad  tracks  the  wear  has  been 
about  an  inch  and  a  half  during  these  three  years,  while  on  the  roads  free 
from  these  tracks  the  wear  has  been  about  one  inch  on  the  crown  and 
perhaps  a  half  inch  on  the  sides. 

The  cash  cost  of  the  Telford  pavement  laid  under  our  direction  in  1875- 
76  was  ninety  cents  per  square  yard. 

The  stone  was  broken  by  a  ten-inch  "  Blake"  stone  crusher  at  the  rate 
of  about  twenty  cubic  yards  in  ten  hours.  The  size  of  the  stones  as  they 
came  from  the  crusher  was :  50  per  cent.,  2  inches  size ;  25  per  cent.,  i% 
to  i  inch  size ,  25  per  cent.,  screenings  and  pea  dust. 

The  cost  of  the  crusher,  engine,  boiler,  &c.,  set  up  complete,  was  about 
$2,500. 

The  cost  of  working  per  day,  independent  of  the  original  cost  of  the 
machinery  and  interest  thereon,  and  also  independent  of  any  royalty  on 
the  stone,  was  found  by  the  contractor  to  be  as  follows  : 

Repairs,  lubricants,  wear  and  tear  on  crusher  and  engine,  about .$".00' 

1  Engineer,  $2  50  ;    1  feeder,  $1.50  ;  1  screener,  $l.5o  ;  5  laborers  quarrying  and  breakii  g 

up  stones  at  $1.00 .  10.50' 

1  team  hauling  sioue 5.00' 

1  Coulhalfton  , 2.50 

Cost  of  preparing  and  crushing  20  cubic  yards  of  stone. . . 
Cost  of  1  cubic  yard,  $1.20. 


122    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

The  roads  built  under  our  direction  in  1878,  and  now  building,  are  the 
same  in  every  particular  as  those  built  in  187  5-76,  except  that  they  occupy 
only  20  feet  in  width  of  the  crown  of  the  road ;  the  steam  roller  was  not 
used,  and  as  it  is  very  difficult  to  obtain  an  abundant  supply  of  water  in 
the  locality,  we  have  to  rely  on  the  rainfall  for  sprinkling,  and  do  all  our 
rolling  in  wet  weather.  A  horse  roller  is  used  of  1 50  pounds  per  inch  run. 

Some  3,000  square  yards  of  these  roads  were  completed  one  year  ago, 
and  have  been,  since  that  time,  subjected  to  a  daily  traffic  of  about  1 50 
wagons,  principally  carts,  loaded  with  stone  and  dirt.  The  surface  of  the 
pavement  is  now  as  nearly  perfect  as  it  is  possible  to  imagine  that  of  a 
macadamized  road  to  be. 

The  cash  cost  of  these  roads  is  eighty  cents  per  square  yard. 

CONCLUSIONS. 

A  Telford  road  imy  be  practically  divided  into  two  parts. 

1.  The  foundation,  which  should   be   uniformly  secure,   and  which 
should  be  at  the  same  time  a  perfect  blind  drain. 

2.  The  superstructure,  which  should  be  a  durable,  water-tight  roof. 

If  these  conditions  are  complied  with — if  proper  materials  are  used  in 
the  construction  of  the  road,  and  reasonable  attention  is  given  to  its  main- 
tenance, the  result  will  be  as  has  been  claimed,  a  durable  road,  unsur- 
passed for  comfort  of  travel,  and  one  to  be  preferred  to  all  others  for  sani- 
tary reasons. 

If  these  conditions  are  not  attended  to  the  road  will  last  but  a  short 
time. 

The  foundation  is  of  the  first  importance.  It  should  be  eight  inches  in 
depth.  More  than  this  is  a  waste  of  material,  and  a  less  depth  is  not  suf- 
ficiently secure  for  want  of  proper  bond.  It  must  be  laid  as  close  as  pos- 
sible by  hand,  then  the  interstices  at  the  top  wedged  and  sledged,  until 
the  small  stones  that  compose  the  superstructure  cannot  work  down,  and 
fill  the  interstices  at  the  bottom  of  the  foundation. 

Too  much  emphasis  cannot  be  given  to  this  part  of  the  work.  It  is 
not  only  essential  to  perfect  sub- drainage  ;  it  is  equally  important  in  the 
great  saving  of  the  cost  of  building  the  road.  A  loose  foundation,  which 
allows  the  small  stones  to  settle  down  upon  the  large  ones,  will  require 
nearly  as  many  again  of  the  small  stones  before  a  proper  surface  can  be 
obtained,  hence  the  cost  of  the  superstructure  will  be  nearly  doubled.  Of 
course,  if  the  small  stones  work  down  among  the  large  stones,  the  latter 
will  work  up  the  surface,  and  ultimately  ruin  the  road. 

An  excellent  test  of  a  foundation,  when  the  substratum  is  firm,  is  to 
drive  a  loaded  truck— weighing  about  three  tons— over  the  pavement  be- 
fore any  of  the  upper  courses  are  placed  thereon ;  if  the  foundation  has 
been  properly  laid  no  ruts  or  other  displacement  will  occur. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    123 

As  to  the  size  of  the  foundation  stones,  we  prefer  them  large  rather 
than  small.  Nothing  is  so  dangerous  as  thin  slabs.  A  large  stone  now 
and  then,  say  ten  inches  wide,  well  bedded,  seems  to  act  as  an  anchor 
for  the  rest,  and  we  have  yet  to  find  an  instance  where  the  small  stones 
have  broken  loose  from  such  a  foundation  stone. 

In  regard  to  the  superstructure,  we  are  convinced  that  if  the  material 
is  crushed  trap,  any  increase  over  four  inches  in  depth  is  a  waste  of 
material.  We  found  this  to  be  the  most  expensive  portion  of  the  road, 
the  cost  of  the  eight-inch  foundation  being  to  the  cost  of  the  four-inch 
superstructure  as  one  is  to  two.  Four  inches  will  answer  all  requirements 
as  well  as  any  greater  depth,  because  after  the  metal  has  worn  down  two 
inches,  the  road,  owing  to  unequal  wear,  will  need  to  have  a  new  coating 
in  any  event,  and  the  amount  saved  in  the  first  cost  and  the  interest 
thereon,  by  making  the  superstructure  only  four  inches  deep,  will  keep 
the  road  in  repair  for  many  years. 

In  regard  to  steam  rolling,  it  is  often  questionable  whether  it  is 
essential,  or  even  desirable,  in  the  building  of  Macadamized  roads,  espe- 
cially when  the  road  is  built  of  New  Jersey  trap  rock. 

The  principal  action  of  the  steam  roller  is  to  crush  the  stone  into  the 
crevices,  and  the  result  is,  that  a  crust  is  quickly  formed.  On  the  other 
hand,  the  horse  roller  rattles  around  and  shakes  the  small  stones  about, 
until  they  are  firmly  bedded  upon  the  rough  but  firm  foundation  and 
upon  each  other.  No  crust  is  formed,  but,  on  the  contrary,  a  compact 
homogeneous  mass,  which  result  is  much  more  to  be  desired.  Attain, 
the  road  bed  upon  which  the  pavement  is  laid  often  varies  very  greatly ; 
frequently  a  rocky  bottom  adjoins  a  soft  stratum;  on  one  side  of  the  road 
may  be  an  excavation  and  the  other  side  a  fill.  In  such  a  case,  a  heavy 
roller  is  much  more  likely  to  disturb  the  uniformity  of  the  foundation 
than  a  lighter  one,  no  matter  how  great  care  may  have  been  taken  to 
provide  for  emergency. 

If  it  be  necessary  to  finish  the  surface  of  the  pavement  within  a  week 
or  two,  a  steam  roller  must  certainly  be  used,  but  we  believe  that  rapidly 
made  roads  are  much  less  durable  than  those  whose  construction  extends 
over  a  long  period  of  time. 

It  required  at  least  three  months  to  finally  form  the  surface  of  the 
roads  built  by  us  in  1875-76,  while  on  the  roads  now  building,  some  of 
the  sections  have  required  as  much  as  six  months.  In  the  meantime,  the 
surface  is  kept  free  from  loose  and  rolling  stones,  so  that  there  is  no 
brutal  pulling  through  the  road  metal. 

After  a  road  has  been  slowly  compacted  in  this  way,  we  believe  the 
surface  will  be  found  much  more  durable  than  that  of  any  rapidly  made 
steam  rolled  road. 

As  to  "binding,"  our  experience  has  been  that  during  the  construction 


124   CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

of  the  road  the  less  foreign  material  used  the  better,  unless,  perhaps, 
along  the  edges  of  pavement  which  has  only  an  earth  support.  In  such 
a  case,  it  is  necessary  to  bind  the  edges  as  quickly  as  possible,  in  order  to 
prevent  the  sides  of  the  road  from  spreading  while  the  surface  is  forming. 
After  that  is  accomplished,  very  little  wear  comes  on  the  extreme  edges  of 
the  road. 

As  an  aid  in  the  rapid  formation  of  a  fine  surface,  a  little  yellow  clay 
placed  just  below  the  upper  course  is  almost  invaluable,  but  when  the 
crust  is  broken  the  danger  is  that  the  surface  will  soon  disintegrate,  while 
if,  instead  of  the  clay,  stone  dust  is  placed  between  the  courses  of  broken 
stone,  and  a  top  dressing  one  inch  deep  of  screenings,  such  as  are  pre- 
sented herewith,  is  spread  over  the  surface  and  is  thoroughly  worked  into 
the  broken  stones,  the  surface  is  equally  fine  and  much  more  durable ;  if 
a  spot  does  loosen  here  and  there,  it  does  not  spread  and  a  little  moisture 
quickly  rebinds  the  loosened  stones. 

Finally,  as  to  the  stones  for  the  superstructure,  we  greatly  prefer 
machine-crushed  to  hand-broken  stones. 

1.  Because  they  are  much  more  uniform  in  size,  each  having  actually 
passed  through  a  revolving  screen. 

2.  Because  the  edges  of  the  stones  are  much  r harper  and  bind  better. 

3.  Because  from  the  machine  alone  can  we  obtain  the  screenings  and 
detritus  which  we  consider  so  essential  for  compacting  the  road  and  for 
satisfactory  top  dressing. 

GEORGE  D.  ANSLEY. — My  experience  is  decidedly  in  favor  of  steam 
rolled  Macadam  or  Telford  roads  over  those  formed  by  horse  roller ;  in 
fact,  I  have  altogether  given  up  the  use  of  the  latter,  and  employ  a  1 5-ton 
Aveling  &  Porter,  the  result  being  far  greater  economy  in  the  end  as  to 
outlay,  and  a  decidedly  smoother  and  more  permanent  surface  is  obtained. 

As  to  compacting  with  traffic,  I  am  altogether  opposed  to  it,  as  being 
inhuman  toward  horses  and  extravagant  in  the  waste  of  material.  I  speak 
of  the  case  when  any  considerable  extent  of  roadway  is  to  be  covered ; 
but  in  small  repairs,  or  what  is  technically  called  "  darning,"  I  first  pick 
up  the  margins  of  the  depressions  to  the  depth  of  an  inch  or  two,  and 
then  flush  up  with  stone  broken  to  pass  through  a  2-inch  ring  ;  the  edges 
of  the  patch  are  then  covered  with  road  grit,  obtained  at  hand  and  pounded 
with  a  rammer.  In  these  repairs  it  is  found  that  the  horses  feet  avoid 
the  fresh  stone,  while  the  wheels  of  the  vehicles  run  over  the  patch  and 
compact  it  gradually  from  the  edges  to  the  centre  and  a  very  good  "mend'* 
is  thus  made. 

In  reading  over  Mr.  North's  valuable  collection  of  short  histories  of 
road  making,  I  was  particularly  attracted  by  the  mention  of  ramming,  on 
page  103.  There  is  a  short  mention  of  a  rammer  8  inches  diameter,, 
weighing  70  pounds.  Although  steam  rollers  are  far  more  satisfactory 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    12$ 

than  horse  rollers,  it  seems  to  me  that  a  s'ill  further  improvement  may  be 
made  by  the  more  general  introduction  of  the  rammer.  In  all  cases  of 
roads,  whether  Telford  or  Macadam,  or  stone  paving,  or  wood  paving,  the 
first  imperfections  are  the  same ;  the  surface  may  not  be  worn  away 
materially,  but  there  are  depressions  or  concavities  that  hold  water.  Our 
block  stone  pavements  get  into  bad  order  chiefly  through  unevenness,  and 
a  heavy  expense  is  incurred  in  repairs,  while  the  hollow  parts  are  found  to 
be  hard  and  well  set,  and  the  blocks  not  worn,  perhaps,  any  more  than 
those  forming  the  better  parts  of  the  road.  A  wooden  pavement  on  one 
of  our  streets  was  condemned  for  being  in  hills  and  hollows ;  although 
incidentally  there  were  rotten  blocks  that  broomed  and  wore  away,  it  was 
found,  on  taking  it  up,  that  the  foundation  was  uneven,  and  this  notwith- 
standing that  it  had  been  steam-rolled  before  the  blocks  were  laid  on,  five 
years  before.  All  this  tells  the  same  tale — the  earthy  foundation  is  of  un- 
equal density. 

Much  more  attention  has  been  paid  to  the  coating  of  stone  or  other 
material  than  to  the  lowest  or  earth  foundation.  When  a  new  road  is 
made,  the  proper  form  may  be  given  to  the  earth  foundation,  and  it  may 
be  steam  rolled ;  inequalities  then  showing  themselves  may  be  flushed  up 
and  re-rolled,  but  a  roller  will  bridge  over  smaller  soft  places  which  still 
remain  unseen  until  the  road  is  completed  and  heavy  traffic  put  upon  it, 
and  then  we  have  saucer- like  dips  in  its  surface,  to  be  repaired  within  a 
short  time  after  the  road  is  made ;  and  although  the  specification  may 
require  that  these  repairs  shall  be  done  by  the  contractor,  the  surface 
being  thus  broken,  the  road  is  never  so  good  afterward  as  it  would  be  if 
undisturbed. 

How  the  rammer  which  Mr.  North  refers  to  was  used  is  not  mentioned ; 
but  if  by  steam  power,  it  might  be  neither  expensive  nor  slow. 

I  am  inclined  to  think  that  the  regular  stroke  of  a  rammer  is  the  only 
method  of  producing  equal  densities  for  roads,  as  well  as  for  other  pur- 
poses, and  that  the  most  important  part  of  road  making  for  its  application 
is  the  earthy  bottom. 

After  the  ramming  to  equal  density,  I  cannot  see  that  Telford's  method 
is  better  than  Macadam's  for  general  adoption;  local  circumstances, 
however,  would  decide  in  each  case. 

After  reading  through  all  the  various  descriptions,  and  adding  my 
own  views  from  observation  and  experience,  I  consider  the  object  to  be 
aimed  at  is  as  near  as  possible,  a  solid  bed  of  stone.  This  certainly  can- 
not be  accomplished  by  putting  on  any  earthy  matter  as  binding.  Broken 
stone  in  thin  layers,  3  to  4  inches,  chinked  with  fine  chippings  or  screen- 
ings until  full,  and  then  watered  and  rolled  with  steam  roller,  will  come 
very  near  the  desideratum.  Of  course  the  lower  strata  may  be  of  stone, 
Jess  hard  than  the  top.  The  size  of  broken  stone  for  the  upper  part  is 


126     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

important.  A  2^-inch  ring  allows  stone  of  considerable  size  to  be  mixed 
with  lesser  ones,  and  it  is  these  larger  ones  that  first  get  loose  and  move 
about  on  the  surface.  For  the  surface  coating  I  prefer  hand  broken  stone 
over  machine  broken,  as  the  form  is  generally  more  cubical  and  less  apt 
to  become  disintegrated. 

Gravel  is  much  more  difficult  to  reduce  to  solidity  than  broken  stone; 
but  where  there  is  a  large  supply,  and  cheap,  it  is  well  to  follow  the 
principle  before  mentioned.  The  gravel  should  be  screened,  and  the 
coarser  sort  laid  on  first  and  then  chinked  up  with  the  finer.  If  this  is 
done,  and  all  coarse  gravel  kept  away  from  the  top  coating,  water  and 
steam  rolling  will  make  a  good  road  in  almost  any  case  without  earthy 
binding.  Earth  matter  works  into  mud,  and  should  be  avoided,  unless 
the  gravel  is  so  round  and  movable  that  nothing  else  will  keep  it  quiet. 

Where  old  paving  is  taken  up,  and  it  is  proposed  to  put  down 
Macadam,  I  consider  that  there  is  the  same  necessity  for  testing  the 
density  of  the  foundation,  and  rendering  it  equal  by  ramming. 

A.  B.  HILL. — In  New  Haven  we  have  tried  several  plans  in  regard  to 
the  binding  material  of  the  Telford  pavement.  Using  an  inch  of  loam 
on  the  crushed  stone,  with  two  inches  of  screenings  over  that ;  also  using 
sand  instead  of  the  loam ;  but  the  best  results  with  us  are  obtained  by 
using  the  trap  rock  screenings  alone,  spread  on  in  thin  layers,  sprinkled 
and  roughly  rolled.  This  makes  a  very  solid,  firm  surface,  which  does 
not  wear  into  ruts  as  soon  as  the  pavements  are  top-dressed  by  the  other 
methods.  The  roller  used  is  the  1 5-ton  Aveling  &  Porter. 

As  the  grades  in  New  Haven  are  generally  very  light,  and  it  is  desira- 
ble to  secure  a  uniform,  smooth  gutter,  the  latter  is  made  of  blue  stone> 
12  inches  wide  and  not  less  than  4  inches  thick,  bedded  in  sand  next  to 
the  curb,  closely  jointed,  well  rammed,  and,  after  the  pavement  is  com- 
plete, thoroughly  grouted. 

A  space  of  three  feet  outside  the  gutter  stone,  between  the  rails  of  the 
horse  railroad  tracks,  and  for  three  or  four  feet  outside  the  rails,  is  laid 
with  stone  blocks. 

The  Telford  pavement  is  16  inches  thick  at  the  centre  and  14  at  the 
sides,  made  up  of  4  courses  of  trap  rock ;  the  first  or  bottom  course  7 
inches  thick  at  the  centre  and  5  inches  at  the  sides  ;  the  stones  of  the  size 
and  placed  as  usually  specified  for  Telford  foundation ;  the  second  course, 
3  inches  thick,  of  stone  simply  raked  out  and  sorted  at  the  foot  of  the 
trap  dikes  (not  "  broken  "  or  "  crushed  "),  varying  in  largest  dimensions 
from  i  inch  to  4  inches,  spread  on  the  first  course  and  rolled  until  solid  ; 
the  third  course,  4  inches  thick  of  "  crushed "  stone,  also  rolled  ; 
the  fourth  course,  or  top-dressing,  about  2  inches  thick  of  screenings, 
spread  on  in  three  layers,  each  layer  sprinkled  and  thoroughly  rolled 
in. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.     127 

The  average  cost  of  the  Telford   pavement  in  New  Haven,  including 
the  Belgian  blocks,  blue  stone  gutters,  crosswalks,  inspecting,  rolling,  &c.> 
was,  for  1876,  $1.1 8  per  square  yard. 
«•    1877,     1.05 
"    1878,    1.15 

E.  LAVOINNE,  Engineer  des  Fonts  et  Chaussees  (through  the  Secre- 
tary).— The  criticism  of  Mr.  North  upon  the  Macadam  roads  in  the  City 
of  Paris  is  to  the  effect  that  owing  to  the  method  of  compacting,  suffi- 
cient stability  is  not  given. to  the  stones  to  resist  the  traffic.  Mr.  Malo  is 
quoted  as  sustaining  this  criticism.  Even  if  the  bad  results  in  Macadam 
pavement  in  Paris  were  something  like  what  Mr.  Malo  describes  in  his 
rather  sweeping  remarks,  the  fair  inference  would  be,  it  seems  to  me,  that 
the  system  of  construction  was  not  the  best  in  that  location  on  account  of 
the  heavy  traffic. 

Macadam  roads  when  introduced  in  Paris  to  replace  the  former  pave- 
ments were  considered  by  many  engineers  as  a  blunder,  on  account  of  the 
cost  of  their  maintenance  and  other  peculiarities.  It  is  certain  that  no 
Macadam  road,  even  if  constructed  under  the  best  conditions,  could  stand 
the  enormous  traffic  existing  in  many  streets,  which  is  not  occasional,  as 
Mr.  North  states  is  the  case  for  some  of  the  Boulevards  of  New  York,  but 
continuous  and  daily  for  most  of  them. 

As  regards  the  construction  of  roads,  the  illustration  of  what  Mr. 
North  calls  the  French  system,  such  as  he  saw  applied  in  the  repairs  of 
some  streets  in  Paris,  hardly  gives  an  exact  idea  of  the  standard  system 
adopted  by  many  French  engineers.  They  generally  consider  that  in  a 
perfect  Macadam  all  stones  should  bear  directly  against  one  another  by 
faces  as  large  as  possible,  not  by  edges,  and  that  the  interstices,  previously 
reduced  to  a  minimum  by  rolling,  should  be  filled  afterwards  with  a  bind- 
ing which  cannot  be  affected  by  atmospheric  influence  nor  give  access  to 
moisture.  Thus  far  they  agree  with  Mr.  North — but  they  disagree  with 
him  as  to  what  is  the  best  binding. 

Instead  of  screenings  or  very  small  stones  with  the  addition  of  dust 
and  water,  they  prefer  to  use  sand  with  a  small  quantity  of  chalky  dust 
employed  when  compacting  is  at  an  end.  They  consider,  contrary  to 
Mr.  North's  theory,  that  when  the  stones,  whose  sizes  vary  between  i  % 
and  "2.y2  inches,  have  been  thoroughly  packed  together  by  rolling  before 
any  addition  of  binding,  so  that  they  move  no  more  under  the  roller,  and 
a  beginning  of  crushing  takes  place,  then  an  addition  of  smaller  stones  is 
useless  for  stability  ;  if  very  small  stones  like  screenings  were  then  added, 
they  would  be  crushed  and  produce  an  excess  of  dust  injurious  to  general 
stability.  Sand,  injected  by  thorough  watering  between  the  stones  is 
not  liable  to  that  objection,  since,  filling  all  the  interstices,  it  tends  to 
equalize  the  pressures  between  the  stones.  The  addition  of  chalky  dust 


128     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

diluted  by  water,  at  the  end  of  the  operation,  fills  the  interstices  between 
the  grains  of  sand  making  with  it  a  sort  of  mortar  and  coating  for  the 
surface.  In  my  own  experience  the  best  results  followed  this  method ; 
the  consolidation  of  the  Macadam  was  very  satisfactory  at  the  end,  rolling 
not  being  spared  before  the  addition  of  binding.  Loose  stones  occurred 
only  at  a  few  points. 

It  may  be  that  the  roads  examined  by  Mr.  North,  in  Paris,  were  con- 
structed in  too  thick  layers  and  too  hastily  permit  the  stones,  prior  to  any 
addition  of  binding,  to  have  the  required  stability,  much  rolling  being 
necessary  for  this  result.  This  may  be  the  reason  why  loose  stones  were 
seen.  If  the  stones  have  not  been  packed  and  wedged  previously  by 
thorough  rolling,  we  cannot  expect  binding  to  make  them  immediately 
compact. 

The  system  mentioned  as  used  in  New  York  (St.  Nicholas  Avenue), 
in  which  stones  of  from  i  to  i%  inches  are  employed  for  he  top  course, 
will,  no  doubt,  do  for  light  travel  (light,  not  heavy  carriages)  ;  but  such 
pavement  would  very  likely  be  destroyed  by  a  heavy  traffic,  as  the  small 
stones  would  then  be  rapidly  ground  and  disintegrated.  From  my  own 
experience  and  that  of  many  engineers  in  France,  I  am  fully  satisfied  that 
the  capital  difference  between  the  roads  in  the  old  Macadam  style  without 
rolling,  and  those  that  are  rolled,  whether  with  steam  or  horse  power,  is 
the  degree  of  internal  wear  ;  as  the  grinding  of  the  stones  by  their  recip- 
rocal friction  or  internal  disintegration  is  much  more  rapid  under  heavy 
traffic  with  the  former  than  the  latter.  In  the  first  case  the  proportion  of 
disintegrated  material,  detritus,  to  the  stone  is  generally  large  after  a  short 
time  ;  very  small  in  the  second  if  proper  care  has  been  given  to  the  work. 

Evidently  much  more  consideration  should  be  given  to  the  internal 
wearing,  which  is  of  serious  consequence  as  to  cost  of  maintenance,  than 
to  the  incomplete  consolidation  of  the  road  immediately  after  rolling, 
which  could  be  remedied  by  more  rolling  or  made  up  afterward  by  the 
traffic  itself  and  by  removing  the  excess  of  binding  material  by  sweeping. 

In  conclusion,  it  is  suggested  that  for  a  fair  comparison  between  the 
different  systems  of  constructing  the  roads,  there  should  be  taken  into 
account  both  the  quantity  and  quality  of  the  traffic,  and  also  the  cost  of 
maintenance  under  the  same  conditions  for  a  fixed  period.  Conclusions 
might  be  different  if  full  consideration  were  given  to  these  points. 

E.  B.  VAN  WINKLE.— I  would  say  that  I  am  familiar  with  the  roads 
Mr.  North  has  been  constructing  for  the  past  few  years  ;  that  is,  with  their 
present  condition,  and  should  like  to  ask  Mr.  North  if  their  present  condi- 
tion bears  any  relation  to  the  amount  of  rolling  he  put  upon  them  ;  for  in- 
stance, the  Southern  Boulevard,  which  I  now  consider  to  be  the  best  of 
these  roads,  and  the  one  that  carries  the  greatest  traffic,  did  that  receive 
the  greatest  amount  of  rolling  ? 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.     129 


E.  P.  NORTH.  —  The  Southern  Boulevard  received  0.859  ton  m^e  Per 
square  yard,  or  5.177  ton  miles  per  cubic  yard,  which  is  more  rolling  than 
any  other  road  constructed  by  me  had,  and  more  than  any  road  known  to 
me  has  had  applied  to  it. 

The  road  has  stood  the  wear  very  well,  though  part  of  it  is  exposed  to 
a  very  constant  breeze  from  the  Sound,  which  deprives  it  of  the  protection 
that  a  layer  of  dust  would  afford. 

The  teams  on  it  were  counted  from  8  A.  M.  to  5  P.  M.,  and  averaged 
about  300,  from  four-horse  teams,  with  six  or  seven  tons  to  the  load,  to 
buggies. 

E.  B.  VAN  WINKLE.  —  Next  to  the  Southern  Boulevard  I  should  place 
the  streets  constructed  by  Mr.  North  in  the  following  order  as  to  degree 
of  excellence,  always  judging  by  their  present  condition  : 

1st.  One  Hundred  and  Thirty-eighth  street;  2d.  One  Hundred  and 
Sixty-seventh  street  ;  and  last,  Mott  avenue.  Please,  if  possible,  state 
which  of  these  received  the  greatest  amount  of  rolling,  and  if  there  were 
any  difference  in  the  quality  and  size  of  the  metal  and  the  material  used 
for  binding. 

E.  P.  NORTH.  —  One  Hundred  and  Thirty-eighth  street,  which  has  two 
courses  of  broken  stone,  each  about  6  inches  deep  before  rolling,  received 
less  rolling  than  the  Southern  Boulevard  ;  the  surface  is  satisfactory  ex- 
cept in  one  place,  where  the  bottom  was  bad  and  mud  worked  up  through 
the  metal  where  there  are  some  loose  stones.  One  Hundred  and  Sixty- 
seventh  street  is  on  a  heavy  grade,  part  being  at  the  rate  of  n  2-10  feet 
per  100,  and  the  rest  with  8  per  100  for  a  maximum.  The  first  was  rolled 
with  both  horse  and  steam  rollers,  the  steam  roller  ascending  by  an  easier 
grade.  Some  clay  hardpan  was  used  here  in  connection  with  the  screen- 
ings, both  to  increase  the  adhesion  of  the  roller  wheels  and  facilitate  the 
compacting  of  the  road  bed.  The  roller,  a  1  5-ton  Aveling  &  Porter,  old 
pattern,  ascended  the  grade  after  the  application  of  the  hardpan.  On  the 
lighter  grades  nothing  but  screenings  was  used  for  binding,  and  the  rolling 
was  done  entirely  by  steam.  This  part  of  the  wheelway  wears  much  bet- 
ter than  that  portion  where  hardpan  was  used.  No  reliable  account  was 
kept  of  the  amount  of  rolling  this  street  received. 

The  circumstances  under  which  the  wheelway  on  Mott  avenue  was 
constructed  are  fully  detailed  in  Transactions,  Vol.  VIII.,  page  no  (May, 
1879).  On  account  of  its  treacherous  bottom  it  probably  received  less 
rolling  per  square  yard  that  any  other  road,  though  it  was  impossible  to 
keep  accounts  of  the  amount  of  rolling  done. 

All  of  these  streets  are  Macadamized  with  two-inch  trap  and  clean  trap 
screenings,  excepting  that  portion  of  One  Hundred  and  Sixty-seventh 
street  mentioned  above. 

B.  F.  MORSE.  —  The  paving  of   the  Cleveland  Viaduct,  west  of  the 


130     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

river,  over  the  arches,  is  laid  with  New  York  Medina  sandstone  ;  the  road- 
way is  42  feet  between  curbstones,  with  a  double  track  street  railroad  in 
the  centre. 

The  ballast  used  was  of  the  best  quality  of  bank  gravel  spread  in  layers 
of  about  five  inches  in  depth.  Each  layer  was  sprinkled  with  water  and 
rolled.  The  last  layer,  or  that  directly  underneath  the  stone,  was  about 
two  inches  deep,  and  was  left  without  sprinkling  or  rolling  to  receive  the 
bed  of  the  paving  stones.  The  surface  of  the  ballasting  was  finished  to 
the  true  crown  of  the  roadway. 

The  pavement  is  laid  with  blocks,  dressed  nearly  parallel  on  top  and 
bottom,  sides  and  ends,  laid  in  courses  transversely  across  the  roadway. 
The  courses  were  from  three  to  four  inches  thick,  and  from  six  to  seven 
inches  in  depth,  and  the  stone  from  seven  to  twelve  inches  in  length 
The  stones  were  set  close  together,  so  that  no  joint  was  more  than  one- 
half  inch  open  for  at  least  two  and  one-half  inches  down  from  the  top 
surface . 

No  gravel  or  sand  was  placed  between  or  on  top  of  the  pavement 
while  it  was  being  laid.  After  the  stones  had  been  set  in  place  in  sections 
of  fifty  to  one  hundred  feet  in  length  of  the  street  a  light  top  dressing  of 
gravel  or  sand  was  spread  over  the  surface  and  swept  into  the  joints  with 
a  steel  splint  broom.  The  pavement  was  then  thoroughly  sprinkled  or 
flooded  with  water.  Then  the  pavement  was  thoroughly  rammed  two  or 
more  times  with  a  paver's  rammer  weighing  about  ninety  pounds  ;  then 
the  pavement  was  again  washed  or  flooded  and  allowed  to  dry  off. 

The  joints  were  then  filled  to  a  depth  of  three  to  five  inches  with  a 
concrete  composed  of  Trinidad  bitumen  and  coal-tar  cement,  distilled  at  a 
temperature  of  not  less  than  600  degrees  Fahrenheit,  and  mixed  in  proper 
proportion,  so  as  not  to  soften  or  become  brittle  under  heat  or  cold,  and 
was  poured  into  the  joints  of  the  pavement  at  a  temperature  of  not  less 
than  300  degrees,  and  then  the  whole  surface  was  covered  with  one-half 
inch  of  fine  gravel  or  sand,  which  completed  the  work. 

The  pavement  on  the  fixed  iron  spans  was  laid  in  the  following  manner : 
Strips  of  oak  plank,  varying  in  thickness  from  one  and  a  half  to  three  inches, 
were  secured  to  the  iron  floor  beams,  running  longitudinally,  to  give  the 
proper  crown  to  the  roadway.  On  top  of  these  longitudinal  floor  beams 
was  laid  a  layer  of  two  and  one-half  inch  plank,  joints  well  broken  and 
spiked  down.  On  top  of  this  layer  of  plank  there  was  laid  two  thicknesses 
of  tarred  roofing  felt,  or  paper,  laid  in  hot  roofing  cement,  and  the  whole 
covered  with  one-fourth  of  an  inch  of  plastic  pitch,  and  over  this  was  laid 
a  layer  of  inch  boards  or  sheathings,  breaking  joints  with  the  plank  under- 
neath, and  thoroughly  spiked  down. 

The  paving  is  what  is  usually  called  "Nicholson,"  and  consists  of  blocks 
four  inches  long  and  three  inches  thick  laid  upon  and  in  rows  across  the 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.     131 

roadway,  with  a  three-fourth-inch  strip,  one  and  one-half  inches  in  depth 
between  the  rows  of  blocks,  and  nailed  to  the  flooring,  the  blocks  breaking 
joints  at  least  two  inches  with  adjoining  row.  The  space  between  the 
rows  of  blocks  was  then  filled  with  concrete,  composed  of  one  part  of  hot 
undistilled  gas  tar  to  two  parts  of  pitch,  mixed  with  clean  lake  sand  and 
fine  gravel,  applied  hot  and  driven  into  the  joints  with  an  iron  blade  and 
heavy  rammer  until  the  spaces  were  even  full.  The  whole  surface  of  the 
paving  and  gutters  was  then  coated  with  a  top  dressing  of  coal  tar  pitch 
and  fine  gravel,  rolled  thoroughly  with  a  heavy  hand  roller.  The  best 
quality  of  seasoned  white  oak  was  used  for  all  the  wood  parts  of  the  pave- 
ment and  plank  floors. 

E.  S.  CHESBROUGH. — I  cannot  state  the  average  wear  of  wood  pave- 
ments ;  I  can  only  state  that  it  differs  very  much  with  regard  to  different 
kinds  and  in  different  localities.  You  can  easily  see  that  very  much  depends 
upon  the  faithfulness  of  doing  the  work  and  the  material  used. 

In  some  cases  in  Chicago  wooden  pavements  have  lasted  ten  years, 
and  even  longer  ;  and  in  others  they  have  become  very  rough  and  uneven 
in  three  or  four  years.  I  am  not  able  to  give  the  precise  average,  but  of 
course  a  great  deal  depends  upon  the  traffic.  In  the  river  tunnels  the 
wooden  pavements  have  worn  out  in  less  than  two  years,  and  where  the 
wheels  were  confined  very  much  to  the  same  tracks  they  make  ruts  in 
a  short  time.  In  other  cases,  where  the  streets  are  broad  and  clear,  and 
the  traffic  is  spread  over  a  large  space,  they  have  lasted  a  long  time ;  in 
some  cases  ten  years.  It  is  impossible  to  give  the  rule  in  regard  to  that 
unless  you  take  into  account  various  circumstances. 

EDWARD  R.  ANDREWS.— I  would  like  to  ask  Mr.  Chesbrough  whether 
at  Chicago  there  is  any  very  perceptible  wear  in  wooden  pavements  until 
decay  sets  in  ? 

EDWARD  S.  CHESBROUGH. — Decidedly ;  I  have  seen  some  worn 
down  more  than  two  inches  without  any  apparent  decay. 

EDWARD  R.  ANDREWS. — Mr.  North  states  that  a  well  made  Macadam 
road,  constructed  with  trap  rock,  is,  after  an  earth  road,  the  pleasantest 
and  safest  known.  But  trap  rock  or  other  really  good  materials  for  making 
Macadam  roads  are  not  available  everywhere,  and,  at  best,  Macadam  roads 
are  only  adapted  for  pleasure  travel  in  parks  or  suburban  towns,  where 
they  can  be  constantly  watered  and  never  allowed  to  get  out  of  repair* 
Macadam  is  not  adapted  for  general  use  in  cities.  Under  heavy  traffic 
the  surface  is  constantly  ground  into  powder,  which  rises  in  dust  in  the 
summer,  and  they  are  very  muddy  in  the  winter.  Even  in  Paris,  where 
the  maintenance  is  most  thorough,  the  streets  being  continually  watered 
in  summer  in  the  manner  described  by  Mr.  North,  and  frequently  washed 
after  a  day  of  unusual  wear,  and  scraped  by  a  large  army  of  cantonniers, 
yet,  after  heavy  rams,  the  mud  is  frequently  nearly  ankle  deep,  and  m  very 


132     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

hot  weather,  during  the  intervals  of  watering,  or  in  frosty  weather,  the  air  is 
filled  with  most  penetrating  dust.  Mr.  Flad  describes  the  same  state  of 
things  in  St.  Louis  ;  and  in  Boston,  when,  in  winter,  there  is  no  snow  to  cover 
the  ground,  and,  on  account  of  the  cold,  the  streets  cannot  be  watered,  the 
dust  is  intolerable ;  and  in  summer,  where,  for  economy's  sake,  watering 
is  neglected,  a  large  part  of  the  material  with  which  the  roads  are  made  is 
blown  into  the  sea. 

The  compressed  asphalte,  so  common  in  London  and  Paris,  when  con- 
structed as  thoroughly  as  it  is  in  those  cities,  and  as  that  on  Fifth  Avenue, 
in  front  of  the  Hotel  Brunswick,  has  been,  is  a  most  excellent  pavement, 
but  it  also  demands  the  most  careful  maintenance.  No  dirt  should  be 
allowed  to  accumulate  upon  it.  In  frosty  or  in  damp  weather  coarse  sand 
or  fine  gravel  should  be  spread  over  the  surface  to  give  a  good  footing  for 
horses — this  is  done  abroad — and  then  it  is  not  slippery.  It  is  very  quiet, 
and,  in  fact,  has  almost  all  the  qualities  needed  in  a  perfect  pavement ; 
but  it  can  only  be  laid  on  levels,  and  is  expensive. 

Stone  Block  Pavements  are  in  many  parts  of  the  country  the  cheapest 
and  possibly  may  be  the  best  where  the  traffic  is  very  heavy,  but  it  is 
emphatically  the  worst  pavement  for  streets  of  residences  or  wherever 
quiet  is  desirable  ;  and  there  is  no  question  but  that  if  the  incessant  din 
from  the  rattling  of  omnibuses,  heavy  teams,  milk  wagons,  &c.,  from 
which  one  suffers  in  large  cities  paved  with  stone  blocks,  could  be  dis- 
pensed with  by  adopting  a  quiet  pavement,  the  length  of  life  of  citizens 
would  be  increased  and  the  general  health  improved.  Such  would  have 
been  the  case  long  ago  in  New  York,  had  it  not  been  that  the  wooden 
pavements. laid  during  the  " Tweed  "  days  were  such  evident  jobs.  In 
London,  wooden  pavements  give  entire  satisfaction.  The  earliest  were 
not  quite  successful,  but  the  defects  in  construction  have  been  remedied, 
and  now  broad  areas  of  heavily  worked  streets  previously  paved  with  stone 
are  being  laid  with  wooden  blocks,  which  are  found  to  wear  satisfactorily. 

In  the  West,  where  stone  for  pavements  cannot  be  had,  wooden  blocks 
are  largely  used  ;  but,  as  wood  is  cheap  and  can  be  replaced  without  much 
expense,  no  sound  principles  are  followed  in  their  construction.  In  the 
Eastern  States,  no  one  will  allow  that  a  wooden  pavement  can  be  good 
except  when  newly  laid,  when  all  agree  that  it  is  delightful.  There  seems 
to  be  an  unwillingness,  even  among  engineers,  to  give  the  subject  the  at- 
tention it  deserves.  All  agree  that  stone  pavements  are  a  curse,  and  that 
it  would  be  a  blessing  if  a  good  substitute  could  be  found,  but  because 
wooden  pavements,  as  they  have  been  made  here,  have  not  been  a  suc- 
cess, condemn  them  as  a  class. 

Mr.  North  has  stated  what  has  been  the  general  practice  in  laying 
wooden  pavements  in  this  country.  Many  methods  have  been  tried,  but 
.they  have  almost  without  exception  been  "  laid  ^N'\\\\  green  or  wet  blocks, 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    133 

more  or  less  thoroughly  dipped  in  tar,  on  a  bed  of  sand,  not  always  well 
rammed,  with  or  without  the  interposition  of  a  tarred  pine  board,  with 
transverse  joints  from  one  to  one  and  a  half  inches  wide  filled  with  gravel 
and  coal  tar,"  and  I  might  add,  the  whole  done  in  a  most  unworkmanlike 
manner. 

The  results  are  what  might  have  been  expected.  The  careless  manner 
in  which  the  joints  have  been  filled,  has  left  many  channels  open  for  the 
admission  of  water,  which  undermines  the  sand  foundation,  so  that  there 
is  an  uneven  subsidence  under  the  passing  wheels,  and  holes,  small  at. 
first,  but  daily  growing  larger,  appear,  so  that  the  surface  is  soon  destroyed- 
The  result  is  but  little  better  when  tarred  boards  are  laid  under  the  blocks. 
This  practice  of  tarring  wet  sappy  boards  and  blocks  seems  to  be  an  in- 
vention to  make  them  decay  as  soon  as  possible.  It  closes  up  the  cells  of 
the  wood,  so  that  the  moisture  cannot  escape ;  fermentation  immediately 
follows,  which  quickly  destroys  the  strength  of  the  fibres  and  reduces  them 
to  punk.  A  pavement,  constructed  in  this  manner,  would  fail,  of  course. 
Thoroughly  seasoned  wood  might  be  benefited  by  the  tarring  process, 
but  green  wood  never. 

Observe  how  differently  wooden  pavements  are  constructed  in  Lon- 
don. Mr.  North  describes  several  methods,  either  of  which  is  vastly  supe- 
rior to  any  of  the  patented  systems  used  here.  A  rigid  foundation  of 
bituminous  or  cement  concrete  is  universal.  This  costs  more  than  sand, 
but  it  is  permanent,  and  will  prevent  the  blocks  from  sinking  under  the 
wheels.  English  engineers,  in  discussing  pavements,  call  the  foundation 
the  true  pavement,  the  blocks  being  the  wearing  surface  only.  The 
"  Henson "  pavement,  with  some  modifications,  strongly  recommends 
itself  to  my  mind  as  the  best  for  this  country.  Instead  of  a  layer  of  tarred 
paper  on  the  concrete,  I  would  use  a  thin  layer  of  pitch,  with  oil  enough 
in  it  to  make  it  permanently  slightly  plastic,  setting  the  blocks  upon  it 
while  hot  and  soft,  using  the  strips  of  tarred  felt  between  the  rows,  and 
driving  the  blocks  together  as  described  by  Mr.  North.  The  tarred  felt 
would  make  a  very  close  joint.  Then  pour  melted  pitch  over  the  whole 
surface,  taking  care  to  fill  every  crevice,  and  upon  this  spread  fine  sharp 
gravel,  which  will  work  into  the  ends  of  the  blocks  and  form  a  surface 
resembling  macadam,  and  afford  a  far  better  footing  than  wide  spaces  be- 
tween the  rows,  which  serve  as  receptacles  for  mud  and  dust.  It  is  easy 
to  keep  this  pavement  clean.  No  water  can  penetrate  it,  so  that  it  will 
not  be  injured  by  frost.  The  blocks  themselves,  if  creosoted,  will  not 
absorb  water,  and  if  laid  without  spaces  between  the  blocks,  the  drainage 
will  be  surface  drainage  solely,  which  is  of  the  first  importance. 

But  the  pavement  would  be  short-lived,  if  green  and  wet  blocks  are.- 
used.  It  is  not  practicable  to  use,  as  Mr.  North  says  is  the  case  in  Lon- 
don, "  wood  better  seasoned  than  the  pine  generally  used  by  house  car— 


134   CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

penters  in  this  country."  Seasoned  wood  cannot  be  obtained  in  sufficient 
quantities  here.  But,  what  is  far  better,  it  can  be  preserved  from  decay, 
I  have  no  faith  in  any  method  of  wood  preservation  for  paving  blocks 
which  does  not  exclude  water.  The  blocks  are  so  short,  that  any  soluble 
preparation  is  quickly  washed  out  of  them,  and,  if  not  made  waterproof, 
they  are  certain  to  absorb  the  seeds  of  destruction  from  the  filth  in  the 
streets.  The  blocks  should  be  well  saturated  with  creosote  oil,  whose 
chemical  constituents  act  preservatively  upon  the.  fibres  of  the  wood,  by 
coagulating  the  albumen  of  the  sap,  while  the  fatty  matters  act  mechan- 
ically in  obstructing  the  pores  of  the  wood  and  keep  the  water  out.  At 
the  same  time,  as  oil  cannot  be  injected  into  wood  full  of  moisture,  the 
thorough  artificial  seasoning,  which  forms  a  part  of  the  process  of  creo- 
soting  as  carried  on  in  this  country,  is  as  useful  to  the  timber  as  any  of 
the  metallic  salt  processes. 

By  thoroughly  creosoting  the  blocks,  expansion  and  consequent  throw- 
ing out  of  the  blocks  is  prevented.  They  will  not  shrink  or  expand. 
The  wood  is  also  rendered  homogeneous,  the  sap  wood  becoming  as 
durable  as  heart  wood.  Looking  to  sanitary  considerations,  the 
creosoted  wooden  pavement  is  perfect.  The  carbolic  acid  contained  in 
the  oil  is  a  powerful  disinfectant,  and  as  the  pavement  described  will  not 
absorb  any  deleterious  substance  from  the  surface,  it  has  only  to  be  kept 
clean  to  maintain  the  best  sanitary  condition.  This  is  far  from  being 
the  case  with  wooden  pavements  laid  on  the  American  plan.  They  soon 
become  a  mass  of  decaying  vegetable  matter,  and,  as  their  powers  of 
absorption  increases  with  their  disintegration,  they  become  filled  with 
corruptible  matter  absorbed  from  the  filth  of  the  street,  and  as  their  sur- 
face becomes  filled  with  holes,  it  is  absolutely  impossible  to  keep  them 
properly  clean. 

A  good  wooden  pavement  is  also  an  inexpensive  one.  The  cost,  includ- 
ing a  cement  concrete  foundation,  6  inches  deep,  would  not  exceed  $3.00 
per  square  yard.  The  system  of  maintenance  adopted  in  London,  of  making 
it  a  part  of  the  contract  of  construction,  would  insure  good  workmanship 
in  laying  the  pavement,  and  a  good  permanent  roadway  afterwards.  It 
would  not  be  difficult  to  find  responsible  and  honest  contractors  willing  to 
take  such  a  contract  at  a  fair  price. 

In  considering  this  subject,  one  should  not  overlook  the  statistics  of 
accidents  gathered  in  London  by  Col.  Haywood,*  which  show  that  a 
London  horse  will  travel  on  granite  132  miles,  on  asphalte  191,  and  on 
wood  446  miles,  before  an  accident  occurs. 

The  actual  wear  of  wooden  blocks  is  very  slight,  as  long  as  the  fibres 
of  the  wood  are  sound.  Mr.  North  states  that  it  is  y%  of  an  inch  per 

*  See  full  reports  in  the  library  of  the  Society. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.   135 

annum  in  the  streets  in  London,  with  the  heaviest  traffic.  Mr.  Geo. 
Frederick  Deacon,  Member  Inst.  C.  E.,  in  a  paper  read  before  the  Inst. 
of  C.  E.,  states  that,  in  Great  Howard  street,  Liverpool,  which  is  a  shop 
street,  with  a  traffic  consisting  chiefly  of  carriages,  amounting  to  about 
94,000  tons  per  annum  per  yard  in  width,  the  pavement  was  worn  to  the 
extent  of  ^  of  an  inch  in  four  years.  This  would  give  a  life  of  nearly 
twenty  years  before  the  blocks  would  be  reduced  from  6  inches  to  a 
thickness  of  3  inches,  which  is  still  sufficient  to  maintain  the  blocks  in 
place. 

In  Oxford  street,  in  London,  where  the  traffic  is  equal  to  300  tons  per 
foot  per  day,  the  amount  of  wear  has  been  found  to  be  from  TV  to  %  inch 
during  three  and  a  half  years.  This  street  is  laid  with  the  Henson  pave- 
ment. This  slight  wear  is  largely  due  to  the  fact  that  the  ends  of  the 
fibres  do  not  broom,  and  thus  retain  their  original  strength. 

C.  SHALER  SMITH. — I  merely  wish  to  ask  Mr.  Andrews — speaking 
of  the  foundations  of  wooden  pavements — if  he  is  aware  of  any  pavement 
being  laid  as  upon  the  Cleveland  Viaduct,  that  is,  Nicholson  pavement 
upon  an  iron  foundation  ? 

E.  R.  ANDREWS. — I  am  not  aware  of  any  except  the  Broadway  Bridge 
in  South  Boston,  where  it  was  necessary  to  have  a  light  pavement.  A 
bituminous  concrete  about  two  inches  thick  was  spread  on  the  top  sheet- 
ing and  allowed  to  become  solid ;  then  a  thin  coating  of  hot  tar  spread 
evenly,  and  creosoted  spruce  blocks,  injected  at  my  works  with  12  Ibs.  of 
oil  per  cubic  foot  laid  in  rows  %  inch  apart,  and  the  interstices  filled  with 
pitch  and  the  surface  spread  with  gravel. 

G.  BOUSCAREN. — Can  you  give  the  cost  of  creosoting  ? 

E.  R.  ANDREWS. — $12.00  to  $16.00  per  thousand  feet,  board  measure. 

G.  BOUSCAREN.— Can  spruce  be  treated  well  ? 

E.  R.  ANDREWS. — Spruce  does  not  absorb  oil  readily  on  account  of 
the  compact  character  of  its  fibres,  yet  it  will  take  in  a  gallon  of  oil  per 
cubic  foot ;  hemlock,  pine,  both  white  and  yellow,  and  porous  oak,  are 
more  absorbent.  Wood  which  is  the  most  destructible,  because  it  ab- 
sorbs water  readily,  is  really  the  best  for  creosoting,  as,  for  instance,  the 
gums  and  cotton  wood. 

G.  BOUSCAREN. — Have  you  any  special  rule  for  determining  the 
amount  of  carbolic  acid  in  the  oil  ? 

E.  R.  ANDREWS. — I  have  not  taken  any  pains  to  ascertain.  The 
quantity  depends  upon  the  character  of  the  coal  from  which  the  gas  was 
made,  varying  from  5  to  10  per  cent.  It  has  been  ascertained,  however 
through  careful  experiments  by  a  Belgian  chemist,  that  the  wood-preserv- 
ing qualities  of  creosote  oil  are  due  rather  to  the  water-proofing  imparted 
to  the  wood  by  the  hydro-carbons  contained  in  it  than  by  the  carbolic  acid. 
The  latter  is  very  volatile,  and  were  it  not  retained  by  the  gummy,  resinous 


136    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

oil,  would  quickly  escape  into  the  air.  In  England  no  reference  is  made  to 
the  quantity  of  carbolic  acid  contained  in  dead-oil  to  be  used  in  the  speci- 
fications for  contract  work.  Carefully  conducted  experiments  of  my  own 
with  pieces  of  yellow  pine,  8  inches  by  8  inches  and  9  feet  long,  have 
shown  that  six  months  after  treatment' they  did  not  absorb  any  water  dur- 
ing a  soaking  of  48  hours  under  water. 

M.  MERI WETHER. — We  made  in  Memphis,  in  1867,  what  has  proved 
to  us  a  very  costly  experiment  in  wooden  pavements.  We  laid  there  in 
that  year  and  the  succeeding  spring  some  225,000  square  yards  of  what  is 
known  as  Nicholson  pavement.  The  streets  on  which  this  was  laid  rise 
six  inches  from  the  side  to  the  centre  of  the  street.  Two  inches  to  two 
and  a  half  of  sand  were  laid  down,  and  that  covered  over  with  an  inch 
board  longitudinally.  Those  boards  were  immersed  in  hot  coal-tar. 
After  that  were  laid  cypress  blocks  eight  to  twelve  inches  long,  with  a 
thickness  of  three  inches,  with  a  cleat  between  them,  tacked  to  them. 
About  one-half  of  that  kind  were  immersed  in  boiling  tar.  According  to 
the  contract  it  was  to  be  red  cypress  wood,  which  is  very  durable  above- 
ground,  and  of  more  than  ordinary  durability  underground,  and  is  found 
to  last  better  than  ordinary  oak  ;  but  the  sap  portion  of  that  wood  is  very 
perishable,  rotting  within  one  or  two  years  if  exposed  above-ground.  The 
heart  will  last  twenty-five  years,  or  so,  in  fences.  I  mention  this  to  show 
the  durability  of  the  material.  Most  of  that  was  entirely  covered  with 
boiling  coal-tar  and  small  gravel,  and  the  interstices  filled  with  sand,  mak- 
ing a  beautiful  pavement  for  about  three  or  four  years.  Some  portions  of 
it,  however,  began  to  show  decay  in  three  years,  where  the  sap  of  the 
block  was  put  in.  The  contractor  got  in  a  good  many  sap  blocks,  and  as 
soon  as  they  began  to  decay  the  adjacent  blocks  were  loosened,  so  at  the 
end  of  about  five  years  it  was  in  many  places  impassable,  and  some  blocks 
were  entirely  destroyed.  The  remnants  of  that  wooden  pavement  of  1867 
and  1868  are  now  there.  The  pavement  cost  us  $3.89  per  square  yard.  I 
am  satisfied  had  the  blocks  all  been  heart  cypress  it  would  have  been  good 
for  perhaps  ten  years.  We  have  portions  of  the  pavement  now  where  the 
heart  of  the  cypress  was  used,  where  there  is  no  surface  wear  perceivable. 
However,  we  are  satisfied  with  that  experiment,  and  I  do  not  think  we 
will  ever  put  down  another  square  yard  of  wooden  pavement  of  any  sort. 
We  are  now  making  arrangements  to  pave  with  granite. 

E.  R.  ANDREWS. — It  seems  to  me  very  clear  that  the  reason  why  the 
cypress  pavement  did  not  last  was  because  the  blocks  were  dipped  in  tar. 
It  is  not  at  all  probable  that  these  blocks  were  perfectly  seasoned,  because 
seasoned  lumber  cannot  be  found  in  this  country  for  paving  purposes, 
hence  the  sap  enclosed  within  the  wood  by  the  tar  soon  fermented  and  the 
fibres  rapidly  decayed.  If  the  blocks  had  been  laid  without  being  dipped 
in  tar  I  think  you  would  have  had  a  very  fair  pavement  now. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  137 

I  would  like  to  ask  as  to  the  condition  of  a  pavement  in  Washington 
called  the  Flannigan  pavement,  with  cypress  blocks  sawed  from  round 
sticks  and  laid  promiscuously,  large  and  small  together,  the  spaces 
being  filled  with  pitch.  I  have  understood  that  that  pavement  has  stood 
well. 

J.  E.  HILGARD. — That  pavement  has  done  the  best  of  any  in  the  city. 
It  was  tried  as  an  experiment  on  Third  street,  near  the  railway. 

The  city  of  Washington  has  made  very  extensive  experiments  in  the 
matter  of  wooden  pavements.  Nothing  was  done  to  preserve  the  bfocks. 
They  were  hemlock  ;  none  of  it  has  lain  in  tolerable  condition  over  four 
years  ;  much  of  it  had  become  intolerable  even  before  that  time.  I  think 
the  work  was  badly  done  from  there  not  being  proper  supervision.  An 
immense  amount  of  work  was  undertaken  to  be  done  within  a  limited 
time.  It  was  the  most  disgraceful  failure  of  wooden  pavements  ever 
known,  and  it  has  been  a  case  of  unprecedented  decay.  None  of  the 
streets  were  in  a  fit  condition  to  travel  over  after  four  years  ;  most  of  them 
have  been  replaced  by  concrete  pavements.  With  us  the  experiment  has 
been  a  very  expensive  one.  Climate  may  have  had  something  to  do  with 
it,  for  it  is  very  warm  in  summer  and  we  have  very  frequent  showers,  but 
certainly  the  decay  was  unusually  rapid. 

E.  R.  ANDREWS. — In  1869,  Columbus  avenue,  in  Boston,  was  paved 
with  wood  ;  every  one  who  had  any  patent  pavement  was  allowed  to  put 
down  a  piece  ;  one  section  was  laid  with  creosoted  blocks,  but  very  imper- 
fectly prepared.  All  the  pavements  were  taken  up  and  the  street  repaved 
with  the  Trinidad  bitumen  in  1877;  but  a  small  delta  of  the  creosoted 
pavement  was  left,  which  is  still  sound  and  in  good  condition. 

M.  MERIWETHER. — I  did  not  mention  that  about  one-half  of  the 
pavement  of- which  I  spoke  was  laid  with  planks  dipped  in  boiling  tar, 
and  after  making  about  one-half  of  it  the  very  difficulty  suggested  by  Mr. 
Andrews  arose,  and  we  ceased  to  immerse  the  blocks,  upon  the  theory 
that  if  the  under  side  was  covered  with  tar  it  would  cost  more,  so  they 
stopped  that  process  and  laid  the  balance  in  the  other  way,  and  after  the 
planks  were  down  they  covered  the  surface  simply  with  coal  tar,  upon  the 
theory  that  the  bottom  of  the  planks,  not  being  concealed,  the  acid  would 
go  down  ;  but  we  did  not  discover  that  it  made  any  perceptible  difference. 
It  would  probably  have  been  satisfactory  if  the  blocks  had  been  heart 
wood,  but  the  sap  of  the  blocks  decaying,  led  to  their  destruction  by  the 
wheels  passing  over  it.  It  was  an  utter  impossibility  to  have  seasoned 
wood  for  such  an  extent  of  pavement — some  225,000  square  yards,  hid  at 
once.  The  wood  was  not  in  the  market,  and  no  one  could  afford  to  keep 
such  a  stock  on  hand.  The  result  was  that  the  wood  was  brought  di- 
rectly from  the  mills  and  put  down  within  two  or  three  months  from  the 
time  it  was  taken  from  the  stump.  I  do  not  think  any  process  short  of 


138  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

thorough  seasoning,  or  some  process  of  drying  quickly  by  steam,  would 
do  any  good.  We  found  it  impossible  to  get  the  heart  cypress  entirely, 
and  the  sap  wood  would  decay  in  two  or  three  years. 

The  blocks  covered  the  surface  and  prevented  the  water  passing 
down,  but  it  may  have  passed  on  the  side.  They  merely  covered  the 
surface  with  tar,  and  some  little  water  might  find  its  way  down  the  side 
of  the  block.  The  spaces  between  the  blocks  were  thoroughly  rammed 
with  small  gravel,  with  sand  with  it,  and  the  surface  covered  with  coal 
tar. 

C.  SHALER  SMITH. — I  have  recently  made  some  experiments  for  the 
St.  Louis  Bridge,  which  illustrate  in  a  marked  degree  the  action  of  those 
preservatives  depending  on  carbolic  acid  for  their  antiseptic  value.  Find- 
ing the  wooden  stringers  of  this  structure  beginning  to  rot  at  the  ends  and 
other  points  of  support,  while  the  remainder  of  each  stick  continued  sound 
and  untouched  by  decay,  I  tried  to  arrest  the  rotting  by  the  injection  of 
creosote  containing  ten  per  cent,  of  carbolic  acid  into  all  these  timbers 
which  showed  signs  of  decomposing  fibre.  The  effect  was  remarkable. 
Sound  wood  was  unharmed,  but  where  decay  had  already  commenced  the 
acid  seized  upon  the  wood  and  converted  all  parts  affected  by  rot  into  a 
brown  cinder,  in  many  cases  absolutely  destroying  the  bearing  value  of 
the  stick.  The  experiment  was  extensively  and  exhaustively  tried,  and  I 
am  satisfied  that  while  creosote  is  excellent  when  properly  applied  to  per- 
fectly sound  lumber,  it  will  not  arrest  decay  when  once  started,  and  in 
many  cases  will  destroy  all  the  unsound  parts  of  a  stick. 

And  also,  that  in  th^  use  of  cresote,  the  proper  proportion  of  carbolic 
acid  is  a  very  important  element,  and  should  be  fixed  by  specification 
whenever  this  system  of  treatment  is  used.  I  have  likewise  continued 
•experimenting  on  other  methods  of  preserving  wood,  three  of  which  have 
given  good  results. 

The  first  is  the  "  Thilmany,  old  process."  This  consists  in  impregnat- 
ing the  wood  with  sulphate  of  copper,  and  subsequently  with  the  chloride 
of  barium.  The  chemical  action  of  the  two  salts  fills  the  pores  of  the 
wood  with  the  preservative  chloride  of  copper,  mechanically  fixed  in  posi- 
tion by  the  insoluble  salt,  sulphate  of  baryta. 

The  second  is  the  "  Thilmany,  new  process."*  Here  the  first  impreg- 
nation is  sulphate  of  zinc,  the  second  chloride  of  barium,  and  the  resulting 
salts,  chloride  of  zinc  fixed  as  before  by  sulphate  of  baryta. 

The  third  is  known  as  the  tan-zinc  process.  The  first  impregnation  is 
with  chloride  of  zinc  dissolved  in  a  solution  containing  2^  per  cent,  of 
glue.  This  is  followed  by  an  injection  of  a  tannin  solution  which  precipi- 
tates the  glue,  forming  tannate  of  gelatine,  a  perfectly  insoluble  com- 

*  For  specifications  of  this  process,  see  Appendix  No.  6. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  139 

pound,  and  which  fixes  the  chloride  of  zinc  so  thoroughly  that  it  cannot  be 
extracted  either  by  boiling  or  steaming.  I  am  not  now  prepared  to  state 
which  of  the  three  processes  is  the  best,  as  our  experiments  are  still  going 
on.  It  may  be  safely  asserted,  however,  that  no  system  of  treatment  de- 
pending on  a  soluble  salt,  as  in  the  Burnett  or  Boucherie  processes,  is  of 
any  value  unless  the  salt  is  fixed  in  the  wood  by  a  subsequent  injection 
which  will  fill  the  pores  with  an  insoluble  substance.  I  have  procured 
specimens  from  various  Burnettized  bridges,  and  the  analysis  has  shown 
in  every  case  that  the  zinc  had  been  entirely  washed  out  of  the  wood. 
In  treating  wood  by  either  the  cresote  or  metallic  salt  systems  the  anti- 
septic injection  is  virtually  worthless  unless  the  wood  has  been  previously 
deprived  of  its  sap.  In  doing  this  the  following  rules  should  be  rigidly 
observed : 

First. — The  steam  bath  should  not  exceed  5  pounds  pressure,  or  240 
deg.  F.  in  temperature,  and  the  lumber  should  remain  in  the  bath  for  not 
less  than  90  minutes  for  sticks  under  ten  feet  in  length,  and  9  minutes 
additional  for  every  additional  foot  of  length. 

Next. — The  steam  bath  should  be  followed  by  an  exposure  to  a 
vacuum  of  not  less  than  1 1  pounds  pressure  for  40  minutes  for  sticks  less 
than  10  feet  in  length  and  6  minutes  more  for  each  additional  foot,  after 
the  vacuum  is  reached. 

Last. — The  preservative  injection  should  be  run  in  while  the  vacuum 
is  still  on,  and  after  the  cylinder  is  filled  the  injection  pressure  should  be 
brought  up  gradually  to  not  less  than  100  pounds.  The  time  for  its  con- 
tinuance will  vary  with  the  wood  used  and  the  length  of  the  stick. 

By  the  observance  of  these  rules  in  treatment  and  the  selection  of 
thoroughly  sound  lumber,  it  is  in  my  opinion  perfectly  practicable  to  pro- 
duce a  good  wooden  paving  block,  which,  when  properly  laid,  will  make 
a  clean  and  lasting  pavement.  Treated  gum  blocks  placed  in  the  testing 
machine  at  the  St.  Louis  Water- Works  stood  the  passage  of  95,000 
wheels  with  a  wear  of  only  one-eighth  of  an  inch.  The  wheels  of  test- 
ing machine  were  loaded  to  2,000  pounds  per  wheel,  or  800  pounds  per 
inch  of  tire  width. 

It  is  hardly  necessary  to  reiterate,  however,  that  no  system  of  treat- 
ment, however  good,  will  arrest  decay,  convert  unsound  blocks  into  sound 
ones,  or  render  blocks  cut  from  dead  trees  fit  material  for  a  pavement. 

E.  R.  ANDREWS. — I  do  not  wish  to  advocate  the  use  of  de- 
cayed timber,  or  to  intimate  that  by  the  process  of  creosoting,  wood  which 
has  lost  its  quality  by  reason  of  decay  can  be  restored  to  its  original 
strength;  but  if  partially  decayed  timber  be  creosoted  the  process  of 
decay  is  arrested,  and  there  may  be  cases  where  it  will  be  advisable  to 
creosote  it,  and  thus  save  for  future  usefulness  timber  which  would  other- 
wise be  valueless. 


140  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

As  an  instance  of  such  an  experiment,  I  quote  from  ^a^.  Journal  of  the 
Society  of  Arts,  London,  June  ist,  1860,  containing  a  paper  by  G.  R. 
Burnell,  entitled  "  On  Building  Woods,  the  Causes  of  their  Decay,  and 
the  Means  of  Preventing  it,"  and  a  discussion  thereon  by  the  members  of 
the  society,  during  which  Mr.  John  Bethell  made  the  following  statement 
(see  page  565). 

"  That  in  timber  where  decay  had  commenced  it  had  been  stopped  by 
the  injection  of  creosote.  He  could  confirm  that  fact  by  stating  that 
about  twelve  years  many  thousand  sleepers  were  packed  upon  the  Lanca- 
shire &  Yorkshire  Railway  some  time  before  being  used.  When  they  were 
about  to  be  used  they  were  found  to  be  more  or  less  decayed,  and  it  was 
a  question  whether  the  whole  should  not  be  sold  for  firewood,  when  it 
was  determined  to  submit  the  sleepers  to  the  process  of  creosoting.  After 
those  sleepers  had  been  down  for  ten  years  it  was  found  that  not  only  had 
the  decay  been  arrested,  but  the  sleepers  were  as  good  as  if  they  had  been 
sound,  new  timber." 

I  do  not  quite  approve  of  General  Smith's  specifications  for  the  treat- 
ment of  timber.  Unless  he  has  positive  proof  to  the  contrary,  I  should 
doubt  whether  large-sized  timber  can  be  properly  dessicated  in  ninety 
minutes.  In  my  own  experience  I  find  that  the  time  required  is  greater 
with  large  timber  than  with  small,  and  in  proportion  to  its  square  rather 
than  its  length.  Wood  is  a  slow  conductor  of  heat,  and  a  1 2-inch  by  12- 
inch  stick  cannot  be  heated  through  to  a  point  of  vaporization  in  ninety 
minutes,  and  the  moisture  cannot  be  withdrawn  until  it  is  vaporized. 
Moreover,  it  will  require  a  vacuum  of  20  to  25  inches  during  several  hours- 
to  withdraw  the  vapor,  so  that  danger  of  decay  from  moisture  within  the 
wood  shall  be  removed.  If  this  is  not  accomplished  before  injection  with 
creosote,  the  effect  will  be  to  close  up  within  the  wood  fermentable  sub- 
stances. Thorough  injection  cannot  be  effected.  The  incompressible 
water  will  not  permit  the  oil  to  permeate  those  portions  of  the  wrood 
where  it  exists. 

Engineers  should  give  time  enough  to  do  good  work.  In  the  practice 
abroad  and  in  this  country,  where  creosoting  is  done  intelligently,  the 
work  is  never  hurried.  Large  piles  and  square  timber  cannot  be  properly 
dessicated  and  creosoted  in  less  than  from  20  to  24  hours.  Such  work 
costs  more  money,  but  is  cheapest  in  the  end.  Paving  blocks  can  be 
treated  much  more  rapidly.  During  the  infancy  of  creosoting  in  this 
country  great  care  should  be  taken  to  secure  thorough  work  in  order  to 
obtain  for  such  timber  the  longevity  attained  in  Europe  and  the  confi- 
dence of  consumers. 

DAVID  E.  McCoMB. — I  shall  confine  my  remarks  to  granite  and 
bituminous  pavements  as  laid  in  the  cities  of  Washington  and  George- 
town, D.  C. 

The  standard  stone  pavement  has  a  base  of  six  inches  of  hydrau'ic  con- 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  141 

•crete,  upon  which  is  spread  three  inches  of  sand,  in  which  the  granite 
blocks,  measuring  eight  inches  by  four  inches  by  six  inches  in  depth,  aver- 
age, are  bedded  with  close  joints,  which  joints  are  filled  with  screened 
gravel,  pea  size,  heated  to  a  temperature  of  400  deg.  F.  The  blocks  are 
then  brought  to  a  solid  bearing  by  the  use  of  the  ordinary  rammers,  after 
which  the  joints  are  filled  with  coal  tar  refined  to  400  deg.  F.,  which 
removes  the  light  oils,  water,  etc.,  yet  retains  the  heavy  oils,  "  cut  back," 
which  is  the  result  ot  a  mixture  of  the  residuum  of  the  destructive  distil- 
lation of  coal  tar,  with  still  bottoms,  being  carefully  guarded  against. 
After  the  joints  have  been  filled  with  the  tar,  as  before  described,  fine 
heated  sand,  or  perfectly  pulverized  limestone,  is  spread  over  the  surface, 
which  completes  the  pavement.  In  situations  where  the  sub-foundation 
is  solid  and  unyielding,  the  concrete  base  is  dispensed  with,  six  inches  of 
gravel,  compressed  by  a  heavy  steam  roller,  being  substituted  in  its  stead. 

All  the  different  kinds  of  tar  pavements  have  been  laid  and  tested  in 
Washington,  and  our  experience  is  that  they  are  not  economical,  requiring 
too  extensive  repairs  and  too  frequent  renewals. 

The  only  two  pavements  that  have  given  any  reasonable  degree  of 
satisfaction  are  those  having  a  mixture  of  Trinidad  bitumen  and  coal  tar, 
refined  to  400  deg.  F.,  in  approximately  equal  proportions  as  the  cement- 
ing medium  of  the  sand,  limestone,  or  other  ingredients  forming  the  body 
of  the  wearing  surface.  Such  a  top  coating  is  good  for  about  seven  years, 
requiring,  however,  watching  and  small  repairs  during  this  time,  after 
which  it  seems  impossible  to  patch  it  successfully. 

There  have  been  laid  six  squares  of  Neuchatel  under  two  different  con- 
tracts, the  first  in  1872,  the  latter  in  1876.  That  laid  in  1872  on  I  street 
has  stood  the  test  of  time  and  limited  travel  very  well,  and  is  in  fair  con- 
dition now.  That  laid  in  1876,  on  Pennsylvania  avenue,  is  in  very  poor 
condition,  and  requires  extensive  repairs.  This  class  of  pavement  possesses 
one  fatal  objection,  viz.,  its  extreme  hardness,  as  a  consequence  of  which, 
when  the  surface  is  covered  with  a  film  of  water,  it  is  only  by  the  exercise 
of  great  care  that  horses  can  travel  upon  it  without  slipping  and  falling 
oftentimes,  especially  in  turning  corners. 

The  pavement  of  this  general  class  that  has  given  the  most  satisfaction 
has  for  its  foundation  a  depth  of  six  to  eight  inches  of  hydraulic  concrete, 
upon  which  is  spread  a  coat  of  asphalt  mastic  half  inch  thick,  which  is 
intended  to  give  an  uniform  surface  to  compress  the  top  coat  upon.  This 
cushion  coat,  as  it  is  termed,  is  composed  of  62  parts  of  fine  sand,  15^ 
parts  of  pulverized  carbonate  of  lime,  and  22  j£  parts  of  asphaltic  cement ; 
all  the  compression  given  to  this  coat  is  that  due  to  rolling  with  a  hand 
roller  weighing  about  ten  pounds  per  inch  run.  The  top  coat,  or  wearing 
surface,  is  composed  of  65  parts  of  fine  sand,  16  parts  of  pulverized  lime- 
stone and  19  parts  of  asphaltic  cement.  The  sand  is  required  to  contain 


142  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

not  more  than  five  per  cent,  of  clay,  and  to  be  a  little  finer  than  would  be 
usually  accepted  for  use  in  making  mortar  ;  the  asphaltic  cement  is  com- 
posed of  refined  Trinidad  asphalte  and  refined  petroleum  still  bottoms,  or 
paraffine  oil  in  the  proportion  of  100  pounds  of  the  former  to  19  pounds  of 
the  latter.  The  pulverized  carbonate  of  lime  is  mixed,  when  cold,  with 
sand  heated  to  300  deg.  F.,  which  mixture  is  then  mixed  with  the  asphaltic 
cement,  heated  also  to  300  deg.  F.,  and  a  thorough  incorporation  is  effected 
in  a  twin  pug  mill,  after  which  the  material  is  carried  in  carts,  having  an 
arrangement  to  keep  it  hot,  to  the  work,  and  is  spread  upon  the  cushion 
coat  with  rakes,  and  having  a  thickness  of  2  8-10  inches.  It  is  then  rolled 
with  the  hand  rollers  before  referred  to,  the  jointings  at  the  curb  being 
tamped  with  the  pilon  described  by  Mr.  North,  which  is  heated  to  a  tem- 
perature of  500-250  F.,  the  test  of  its  being  too  hot  is  that  it  scorches  a 
white  pine  plank,  on  hand  for  the  purpose  of  trial.  The  surface  is  then 
rolled  with  a  steam  roller  weighing  300  Ibs.  per  inch  run,  of  large  disk. 
No  difference  is  observable  between  rolling  with  cold  or  heated  roller. 
The  disks  of  the  roller  are  kept  moistened  with  crude  petroleum,  which 
prevents  any  tendency  to  pick  up  the  top  coat,  and  when  the  proper  pro- 
portions are  observed  no  trouble  is  experienced  from  the  machine  shoving 
the  material  ahead,  this  occurring  when  the  mixture  is  too  rich  in  asphaltic 
cement.  After  being  compressed,  the  thickness  of  wearing  surface  is  two 
inches. 

The  gutters  are  paintwithed  asphaltic  cement  ironed  in,  the  object 
being  to  prevent  the  degradation  that  occurs  at  this  portion  of  the  carriage- 
way, caused  mainly  by  the  fact  that  this  portion  of  the  carriageway  does 
not  share  with  the  traffic  compression  produced  at  the  other  parts  of  the 
roadway. 

Trouble  has  been  experienced  on  pavements  alongside  of  street  rail- 
road tracks,  the  cross  ties  of  which,  if  not  well  ballasted,  move  up  and 
down  sufficiently  to  break  the  pavement  over  them  and  leave  ugly  ridges. 
The  tendency  to  cut  into  ruts  alongside  of  the  rail  is  counteracted  by  laying 
granite  blocks,  eight  inches  by  four  inches  by  six  inches,  alternately  as 
header  and  stretcher,  bedded  in  mastic,  the  toothing  thus  formed  obviating 
this  tendency  to  rut. 

The  above  described  pavement,  when  honestly  proportioned  and  laid, 
possesses  all  the  elements  which  go  toward  making  a  good  pavement,  and 
it  is  not  expensive,  costing  at  the  present  time  about  $1.75  per  square  yard. 

I  agree  with  Mr.  North  that  a  bond  for  maintenance  for  a  term  of  years 
should  be  required  from  the  contractor  for  this  class  of  work,  there  being 
so  much  of  honesty  and  skill  required  in  refining  and  manipulating  the 
materials  composing  it. 

E.  P.  NORTH.— I  would  like  to  ask  Mr.  McComb  how  much  clay  is  left 
in  Trinidad  bitumen  and  how  it  is  refined. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  143 

D.  E.  McCoMB. — There  is  supposed  to  be  left  in  the  refined  bitumen 
twelve  per  cent,  of  impurities,  it  being  practically  impossible  to  refine  it  so 
that  it  will  have  a  smaller  percentage  of  impurities  than  that. 


NOTE  ON  THE  NOMENCLATURE  OF  BITUMENS. 
BY  EDWARD  P.  NORTH. 

While  such  strenuous  efforts  are  being  made  for  uniformity  in  the 
matter  of  measures,  the  nomenclature  of  bitumens  should  secure  attention. 

In  Paris,  and  in  France  generally,  the  nomenclature  of  M.  Malo  and 
others,  as  given  in  Transactions,  Vol.  VIII.,  page  121  (May,  1879),  is  used. 
Colonel  Haywood  also  employs  it  in  the  specifications  and  reports  of  the 
City  of  London,  and  it  is  believed  that  all  dealers  and  manufacturers  of 
asphaltes  use  the  same  nomenclature. 

On  the  other  hand,  in  this  country  dealers  in  Trinidad  bitumen  and  its 
mixture  almost  invariably  call  their  compounds  asphalt  or  asphaltum, 
Tar  pavers  and  roofers  also  apply  the  same  names  to  their  products,  both 
calling  such  asphaltes  as  are  capable  of  compression  Neuchatel,  apparently 
because  the  Val  de  Travers  asphalte  happened  to  have  been  imported  into 
this  country  by  a  branch  of  the  "Neuchatel  Asphalte  Company,  Limited," 
of  London,  which  bought  out  "La  Societe  Generale  de  Asphaltes  de 
Suisse,"  but  could  not  take  the  name  Val  de  Travers,  as  there  was  at  that 
time  an  organized  company  in  London  bearing  that  name,  Val  de  Travers 
asphalte  is  not  called  Neuchatel  in  any  part  of  Europe,  besides  which  there 
are  at  least  three  other  asphaltes  that  can  be  compressed,  besides  many 
others  that  are  used  for  mastics. 

As  the  distinction  between  asphalt  or  asphaltum  on  the  one  hand,  and 
asphalte  on  the  other  is  too  slight  to  attract  attention  of  any  but  a  critical 
reader,  the  advisability  of  following  Malo's  nomenclature  is  submitted  to 
the  Society  as  the  most  logical  and  convenient. 

F.  RINECKER,  of  Wurzburg,  Germany  (through  the  Secretary). — Be- 
sides the  methods  of  paving  described  in  the  paper  of  Mr.  North,  the  fol- 
lowing may  be  worthy  of  a  short  mention  : 

Brick  pavement,  especially  in  Holland,  where  very  hard  brick,  Klinker,  is 
used  for  this  purpose. 

Flag  pavement,  in  many  Italian  towns,  consisting  of  large  slabs,  laid  in 
rows  for  the  wheels  to  run  over,  the  balance  of  the  street  being  com- 
mon pavement. 

Concrete  pavement,  which  (if  I  am  correct)  was  tried  in  Paris  and  New 
York.  I  am  ignorant  of  the  results,  however.  I  have  seen  some 
sidewalks  and  depot  platforms  in  Germany,  which  wear  well.  For 
traffic  it  will  be  worthy  of  consideration,  whether  the  broken  stone  or 
gravel  used  in  the  concrete  should  not  be  of  the  same  hardness  as 
the  cement  to  insure  equal  wear.  In  using  harder  stone  the  unequal 
wear  might  be  a  cause  of  failure. 


144  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

In  selecting  any  system  for  covering  roads  and  streets  uniformity  is 
necessary  throughout  a  whole  city,  at  least  in  its  main  thoroughfares. 
The  safety  of  horses  greatly  depends  on  their  shoes,  but  the  patterns  of 
the  shoes  differ  with  the  roads  on  which  they  are  to  be  used.  The  con- 
nection between  shoes  and  roads  needs  no  comment,  and  in  my  opinion  it 
is  a  grave  mistake  to  use  stone  in  one  street  and  wood  in  another,  when 
the  same  traffic  has  to  run  over  them  both. 

I  attach  some  notes  taken  from  German  and  French  periodicals,  the 
figures  of  which  I  have  reduced  to  United  States  standards. 

As  to  the  cost  of  some  pavements  to  the  square  yard,  the  Deutsche 
Bauzeitung,  1877,  has  the  following  : 


Vienna.  , — London. - 


Granite.  Granite.  Asphalte.  Wocd. 

Durability,  years 35  15.6  17  11.34 

Cost  of  construction $3.07  to  $3.37  $3.77  $3.80  $3.20 

Total  cost  of  maintenance 1.74  1.40  3.27  3.37 

Aggregate  cost  averaging  to  one  year.                      13  .37  .34  .62 

From  experience  at  Buda  Pesth  the  following  data  for  1 5  years  are 
furnished : 

^—Granite  on— N  Trachyte  on  Asphalte  corn- 
Broken  Broken  prim6*  on 
Stone.    Concrete.  Stone.  "Wood.  Concrete. 

Thickness  of  pavement,  inches 7.1             7.1  7.1  ?  2.36to2.76 

"          "   foundation 6.3             6.8  6.3  ?  9.7 

Cost  of  construction $4.50         $5.05  $5.50  $3.00  $4.35 

Total  cost  of  muimenance 2.40           1.80  3.00  6.00  3.00 

Aggregate  cost  of  15  years,  averaging  to 

one  year,  cents 46             .45  .57  .60  .49 

The  paving  stones  of  Paris  are  described  in  "  Romberg's  Zeitschrift  f. 
pract.  Baukunst,"  1878,  as  follows  : 

According  to  the  specifications  a  distinction  is  made  between  large  and 
small  blocks. 

Large  blocks  to  be  7.9  to  9.2  inches  long,  6.3  to  9.2  inches  wide  and  7.9 
to  9.2  inches  high. 

Small  blocks  to  be  6.3  inches  long,  3.9  inches  wide  and  6.3  inches  high. 
The  latter,  "paves  de  petit  echantillon,"  are  preferred  of  late.  Differences 
in  size  to  0.4  inch  are  admitted. 

On  account  of  the  bond,  a  certain  percentage  to  be  blocks  one  and 
one-half  times  as  long  as  specified  above,  "boutisses." 

According  to  the  dressing,  two  qualities  are  distinguished  :  smooth  and 
rectangular  blocks  for  joints  of  only  0.2  inch,  and  rough  ones  for  joints  up 
to  0.6  inch. 

The  material  is  sandstone,  "gresd'yvette  des  Vosges"  or  "deVOurthe" 
and  porphyry  from  Belgium  and  Bavaria.  This  porphyry,  however,  has 
not  given  satisfaction,  wearing  too  smoothly. 

The  price  is  $44  to  $125  the  thousand,  and  $8  to  $13  additional  for 
dressing. 

The  Macadam  is  being  replaced  where  annual  repairs  exceed  50  cents 
the  square  yard. 

*  Asphalte  comprime  ia  the  French  term  for  the  compressed  powder. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.  145 

As  to  the  cost  of  the  Paris  pavements,  the  following  notes  are  from 
"Annales  des  ponts  et  chausse"es,"  1877  and  1878  : 

Pavement.      Macadam.        Asphalte. 

Cost  of  construction $2. 55  to  $3. 45  ?  $1.93  to  $2.42 

Annual  cost  of  maintenance,  cents 9.6  29.0  17.7 

The  wear  of  Macadam,  amounting  to  23.37  cubic  yards  to  the  mile 
and  100  horses. 

Annual  cost  of  maintenance  to  the  square  yard  : 

1872-5.  1876.  1878- 

Pavements,  cents 7.7  8.2  8.5 

Asphalte,        «•     19.3  20.9  20.4 

Macadam,       "     29.0  84.0  32.2 

The  watering  with  carts  costs  : 

On  Macadam 19.3  cents  to  1,000  square  yards. 

On  pavements 9.6      " 

J.  B.  Dumas,  Assistant  Engineer  of  the  City  of  Paris,  published  com- 
parative estimates  in  "  Nouv.  Ann.  de  la  Constr.,"  1878-79,  from  which 
the  following  data  are  compiled  : 

Price  to 
Cost  of  construction.  the  yard. 

Pavement  of  rectangular  blocks  "firres,"  8.9  by  6. 3  by  6. 3  inches $3.22 

Macadam  of  silex 1 . 61 

'•         "  meuliere 1.84 

"         "  porphyre 1.98 

Asphalte  coniprime,  2  inches  thick  on  3.9  inches  concrete. 

Using  for  the  latter  hydraulic  lime 2.98 

"         Roman  cement 8.08 

"  "         Portland 8.15 

Each  inch  of  asphalte  above  2  inches  additional 1 .05 

Wood  pavement,  Trenaunay 2.76 

Norm 4.31 

Annual  cost  of  maintenance  and  repairs: 

Rapaving 24  to  64  cents. 

Asphalte,  roadway 21 

'•         crossings 82     " 

"         sidewalk 4.8" 

Macadam,  silex 47     '• 

'  •          meuliere 55     ' 

"          porphyre 129 

Wood  pavement 56     " 

Both  systems  of  wood  pavements  failed  in  streets  with  high  traffic. 
Experiments  with  asphalte  coule*  have  shown  its  unfitness  for  wagon  traffic. 

THE  ENGINEER,  1878,  Vol.  XLVI.,  p.  358,  ascribes  the  invention  of  the 
Macadam  to  John  Lochhead  in  1794. 

J.  J.  R.  CROES. — Referring  to  the  amount  of  water  used  for  keeping 
down  the  dust  on  Macadamized  roads  (p.  82),  the  following  may  be  of 
interest. 

In  the  year  1872  an  account  was  kept  of  the  water  used  on  the  drives 
in  the  Central  Park  in  New  York  City. 

The  length  of  carriage  ways  is  9.435  miles,  of  widths  'from  30  to  60 
feet,  averaging  54  feet.  The  area  occupied,  including  spaces  for  car- 
riages in  waiting,  is  very  nearly  250,000  square  yards.  The  carts  used  for 
watering  are  in  the  form  of  a  segment  of  a  cylinder  of  35  inches  diameter, 

*  Asphalte  coule  (poured)  is  the  French  term  for  mastic. 


146     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

the  height  being  26%  inches  and  the  chord  20  inches.     The  barrel  is  90^ 
inches  long,  and  contains  40.7  cubic  feet  of  water. 

During  the  season  of  1872,  from  April  ist  to  October  3  ist,  the  roads 
were  sprinkled  on  136  days,  using  81,305  barrels  of  water,  or  3,309,114 
cubic  feet,  an  average  of  24,332  cubic  feet  per  day,  or  97^  cubic  feet  per 
day  for  each  1,000  square  yards.  The  greatest  amount  used  in  any  one 
day  was  on  July  ist,  when  the  temperature  ranged  from  77  degrees  to  93 
degrees  F.,  and  929  barrels  or  37,810  cubic  feet  of  water  were  used  ;  an 
average  of  151^  cubic  feet  per  1,000  square  yards. 

The  next  greatest  amount  used  was  on  June  22d,  when  the  temperature 
ranged  from  70  degrees  to  86  degrees  F.,  and  890  barrels  or  36,223  cubic 
feet  of  water  were  distributed ;  an  average  of  about  145  cubic  feet  per 
1,000  square  yards. 

At  least  one-half  of  the  area  watered  was  sprinkled  twice  as  often  as 
the  other  half,  in  consequence  of  its  greater  exposure  and  the  greater 
travel  upon  it. 

I  am  informed  that  during  the  summer  of  1879  the  carriage  way  of 
Fifth  avenue  from  Twenty-third  to  Thirty-fourth  streets,  0.55  mile  in 
length  and  40  feet  wide,  embracing  12,907  square  yards,  was  kept  watered 
by  six  carts  holding  70  cubic  feet  each,  and  making  from  three  to  six  trips 
per  day.  This  would  make  the  amount  of  water  used  from  97.5  to  195 
cubic  feet  per  1,000  square  yards.  The  pavement  is  of  trap  blocks. 

E.  B.  VAN  WINKLE. — Referring  to  Mr.  North's  paper  :  The  form  of 
roller  proposed  for  the  upper  layers  of  earth  roads,  namely,  large  and 
smaller  sized  disks  placed  alternately  on  the  axis  of  the  roller,  I  have  seen 
used  with  excellent  effect  on  an  embankment,  and  it  could  doubtless  be  so 
used  for  the  foundation  of  earth  roads,  but  is  unsuitable  for  surfacing  and 
road  maintenance.  The  ridges  left  by  the  use  of  this  form  of  roller  would 
tend  to  carry  surface  water  longitudinally  instead  of  the  shortest  distance 
transversely  to  the  gutters. 

I  believe  it  would  be  found  very  efficacious  and  economical  in  the  main- 
tenance of  earth  roads  to  have  the  regular  passage  over  them — one  or 
more  times,  according  to  their  importance — of  a  moderately  heavy  two- 
horse  roller  a  few  hours  after  the  cessation  of  rains.  About  one  roller  to 
every  twenty  miles  of  ordinary  road  should  be  kept  provided. 

Referring  to  page  65  :  I  should  think  it  questionable  whether  the  addi- 
tion of  hard  pan  to  a  clay  road  would  be  of  use. 

Referring  to  pages  68  and  69 :  It  would  be  interesting  to  know  the 
results  of  a  combination  of  the  first  and  last  of  the  systems  of  rolling 
Macadam  roads  enumerated  by  Mr.  North,  that  is,  steam  rolled  and  traffic 
made.  I  would  suggest  that  the  steam  roller  be  first  used  without  bind- 
ing material,  or  with  very  little,  to  bring  the  road  metal  to  a  passable  sur- 
face, and  then  open  the  road  to  traffic. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.      147 

My  experience  coincides  with  that  of  Mr.  North — that  the  hardest  kind 
of  stone,  if  of  the  proper  size,  will  produce  a  firmer  roadbed  when  traffic 
made,  without  softer  binding  material. 

Referring  to  page  71  :  The  reason  why  the  Macadam  in  Basnat  street, 
Liverpool,  does  not  show  the  wearing  qualities  of  a  well-puddled  trap 
road  I  conceive  to  be  not  on  account  of  the  binding  material — coal  tar, 
pitch,  &c. — but  owing  to  imperfect  consolidation  due  to  hand  rolling. 
I  have  no  doubt  that,  the  rolling  being  equal  in  all  cases,  a  binding 
material  of  pitch  as  described  would  give  better  results  than  where  cement, 
clay,  or  "  hoggin  "  were  use'd,  as  less  water  would  reach  the  foundation, 
and  the  pitch  would  have  more  elasticity,  giving  somewhat  without  break- 
ing or  crushing. 

Referring  to  page  72  :  M.  Malo's  picturesque  description  of  the  Macada- 
mized streets  of  Paris  will  apply  with  equal  force  to  London  or  New  York. 

As  far  as  I  have  any  experience,  Macadam  pavements  are  a  failure  for 
city  streets,  except  in  some  isolated  cases  where  the  traffic  is  merely  nom- 
inal, or  where  all  other  considerations  except  pleasure  driving  are  out  of 
the  question. 

Referring  to  page  78  :  One  great  reason  for  the  unexpected  success 
of  Mott  avenue  was,  in  all  probability,  that  the  heavy  rolling  over  the  sat- 
urated fresh  filling  of  earth  of  the  road  (some  four  or  five  feet  in  depth) 
most  thoroughly  compacted  it,  hence  giving  subsequently  a  very  solid 
foundation  for  the  Macadam. 

Referring  to  pages  81  and  82:  The  transverse  section  of  a  pavement 
is  most  important.  The  general  tendency  is  to  give  too  much  crown  to 
the  pavement.  In  streets  where  there  are  horse  railroads  this  crowning 
has  generally  become  excessive,  the  trackmen  tending  always  to  raise  the 
track  regardless  of  any  established  street  grade,  while  the  city  employe's 
who  repair  the  pavements  meekly  assume  that  the  track  is  at  grade  and 
pave  flush  with  it,  while  at  the  same  time  the  curb  is  maintained  at  grade 
or  settles  below  it.  It  would  seem  proper  that  the  authorities  in  charge 
of  street  roadways  should,  at  the  time  a  railroad  is  being  built,  determine 
a  proper  profile  for  it.  This  profile  should  be  filed,  and  the  railroad  forced 
to  conform  to  it. 

Another  fallacy  is,  that  an  excessive  amount  of  crowning  adds  to  the 
strength  of  the  pavement  on  the  principle  of  an  arch,  the  paving  blocks 
being  the  voussoirs  and  the  curbstones  the  skewbacks.  The  absurdity 
of  this  illusion  is  readily  apparent  if  we  conceive  of  an  arch  of  30  to  60 
feet  span  with  a  versed  sine  of  one  foot  or  less,  skewbacks  half  a  foot 
thick  resting  on  compressible  earth,  and,  more  wonderful  still,  the 
voussoirs  in  contact  only  at  the  extrados.  The  greater  the  crown  given 
to  a  pavement  the  less  will  the  depressions  resulting  from  poor  paving  be 
noticeable  on  account  of  holding  water. 


1^8     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

In  an  earth  road  the  transverse  slope  should  never  be  less  than  the  longi- 
tudinal slope.  The  restriction  I  consider  unimportant  in  a  stone  block 
pavement,  as  with  this  class  of  pavements  there  is  no  danger  of  ruts  being 
formed  by  running  water,  while  it  is  quite  desirable  to  have  the  rainfall 
scour  quite  an  extent  of  the  pavement  surface  before  reaching  the 
gutters. 

Gillespie  says  that  the  proper  section  of  roadway  surface  should  be 
formed  by  two  planes  inclined  from  the  gutters  upward  towards  the  centre 
of  the  roadway,  with  their  intersection  rounded  by  a  slight  curve. 

That  this  is  correct  I  have  tried  to  believe  for  a  long  time,  but  obser- 
vation convinces  me  that  it  is  not  the  best  form.  The  arc  of  a  circle  is 
practically  the  best  cross  section  for  street  pavements.  If  not  from  choice, 
at  least  from  necessity,  the  bulk  of  travel  is  along  the  centre  of  the  street, 
the  portions  on  each  side  next  the  curb  being  occupied  by  vehicles  stand- 
ing. With  a  section  of  the  arc  of  a  circle  the  centre  of  the  roadway  is  al- 
most level.  Another  advantage  is,  that  while  the  gutters  are  running 
full,  the  width  of  deep  water  is  narrower  than  when  the  surface  is  an  in- 
clined plane. 

Referring  to  page  83 :  I  fully  agree  with  Mr.  North  as  to  the  excel- 
lence of  granite  pavements  in  England.  London,  particularly,  excels  in 
the  quality  of  its  stone  block  pavements.  I  have  seen  nothing  elsewhere 
equal  to  them  for  streets  of  heavy  traffic.  Their  great  superiority  arises 
principally  from  their  concrete  foundations.  It  is  surprising  that  similar 
foundations  are  not  always  used  when  the  streets  in  the  business  portion 
of  the  city  are  relaid  with  stone  blocks.  The  filling  of  the  joints  between 
the  blocks  with  pitch  I  think  would  be  a  decided  improvement  upon  the 
London  plan  of  grouting. 

Referring  to  page  84  :  Wood  pavements,  as  far  as  I  have  any  experi- 
ence, have  been  without  exception  a  failure.  I  can  conceive  that  creosot- 
ing  the  blocks  and  filling  the  joints  with  bitumen  would  prevent  decay, 
and  thereby  materially  lengthen  the  life  of  this  class  of  pavements,  but,  so 
far,  nothing  has  been — and  in  all  probability  never  will  be — invented  that 
will  prevent  wood,  when  subjected  to  an  incessant  impact  and  attrition  of 
iron  horseshoes  and  heavily  loaded  steel  tires  from  acting  as  wood — that 
is,  quickly  wearing  down.  The  pits  in  the  surface  of  wooden  pavements 
have  been  proved  by  borings  to  be  due  much  more  to  the  actual  wearing 
off  of  the  wood  than  to  settlement. 

Referring  to  page  97 :  My  recollection  of  those  sidewalks  in  Paris 
covered  with  asphaltic  mastic  ("  bitumen"  so  called)  is,  that  they  are  not 
very  satisfactory.  During  July  and  August  alrriost  every  footstep  left  an 
impression  in  the  mastic,  and  in  winter  they  were  excessively  muddy,  and 
had  generally  sunk  out  of  plane. 

Have  any  experiments  ever  been  made  with  the  bituminous  limestones 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    149 


found  in  this  country,  to  use  them  as  paving  material  in  the  same  manner 
as  the  regular  asphalte  ? 

JOHN  BOGART. — Experiments  were  made  some  years  ago  in  Chicago 
with  a  peculiar  limestone,  which  it  was  thought  might  be  utilized  in  a 
manner  similar  to  the  imported  asphalte.  The  result  was  a  good  Mac- 
adam pavement,  but  apparently  the  impregnating  matter  had  no  advan- 
tageous effect — my  recollection  is  that  it  was  petroleum  rather  than 
bitumen,  and  that  it  did  not  exert  any  cohesive  force. 

C.  C.  MARTIN. — The  Smith  Hydraulic  Stone  Crusher  as  now  manu- 
factured possesses  two  peculiarities  which  render  it  superior  in  certain 
respects  to  former  patents  : 

First. — The  power  is  applied  through  an  hydraulic  cylinder,  which 
has  connected  with  it  a  safety-valve. 

Second. — The  opening  through  which  the  stones  pass  after  being 
crushed  is  wider  at  the  bottom  than  at  the  top,  as  shown  by  the  cross- 
section  at  c  c. 

These  are  the  two  essentially  novel  and  good  features  of  the  machine ; 
all  of  the  rest  are  simply  mechanical  arrangements  for  transmitting  the 
power  from  the  engine  to  the  machine,  and  may  be  arranged  as  here  shown 
or  in  any  other  way.  In  this  machine  a  is  the  hydraulic  cylinder,  b  is  the 
frame,  c  is  the  movable  jaw,  */the  toggle,  e  the  hydraulic  ram, /the  plunger, 
g  the  connecting  rod,  h  the  band -wheel,  k  the  fly-wheel,  /  the  stationary 
jaw  ;  the  section  c  c  is  a  front  elevation  of  the  stationary  jaw.  When  the 
machine  is  to  be  made  ready  for  use  the  ram,  e,  is  drawn  back  so  as  to 
place  the  movable  jaw,  c,  far  enough  from  the  fixed  jaw,  /,  to  permit  stones 
of  the  largest  required  size  to  pass  through  between  them  ;  the  plunger,/, 
is  drawn  up  out  of  the  hydraulic  cylinder,  a,  and  the  cylinder  is  then  filled 
with  water  or  other  liquid,  and  the  safety-valve  is  weighted.  The  opera- 
tion of  the  machine  is  as  follows :  Stones  are  thrown  between  the  jaws 
and  the  engine  started  ;  as  the  crank  shaft  revolves  the  plunger,/  is  forced 
down  into  the  liquid,  and,  displacing  a  portion  of  it,  forces  the  ram  for- 
ward, which,  through  the  toggle,  d,  presses  the  movable  jaw  against  the 
stone,  which  is  crushed.  The  upward  movement  of  the  crank  withdraws 
the  plunger,  and  the  ram  is  drawn  back  to  its  original  position,  and  the 
jaw  is  again  opened  :  thus,  every  revolution  of  the  crank  shaft  produces 
one  stroke  of  the  jaw.  The  machine  works  well,  running  at  two  hundred 
to  two  hundred  and  fifty  revolutions  per  minute,  and  will  readily  and 
regularly  break  seventy-five  cubic  yards  of  limestone  in  ten  hours  to  sizes 
varying  from  i  %  to  2.%  inches  largest  dimensions. 

The  advantage  of  the  safety-valve  is,  that  in  case  any  stone  which  can- 
not be  broken,  a  sledge-hammer  dropped  from  the  hands  of  a  careless 
workman,  or  any  other  unyielding  body,  gets  between  the  jaws,  the  only 
Effect  is  to  force  open  the  safety-valve  and  permit  the  escape  of  a  portion 


ISO   CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 


\ 

HYDRAULIC    STONE    CUTTER    (SMITH'S    PATENT). 

discharged  is  received  in  a  small  tank,  and  the  continued  motion  of  the 
machine  pumps  it  back  into  the  cylinder,  and  the  crushing  goes  on.  If 
of  the  liquid  from  the  cylinder,  thus  stopping  the  motion  of  the  jaw  with- 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    151 

out  stopping  or  changing  the  motion  of  the  fly-wheel,  The  liquid  thus 
the  obstruction  still  continues,  the  safety-valve  is  again  opened.  The  result 
of  this  safety  attachment  is  that  the  machine  is  never  broken. 

The  advantages  of  widening  the  jaw  at  the  bottom  are  twofold,  as 
will  appear  from  a  consideration  of  the  operation  of  the  stone  in  the 
crusher.  The  broken  stones  occupy  more  space  than  the  unbroken,  and 
the  smaller  the  pieces  the  more  space  do  they  occupy.  The  stone  enter- 
ing at  the  top  of  the  jaw  is  broken,  and  each  successive  stroke  crushes  it 
more,  and  in  the  old  style  of  jaw  the  stone  became  clogged  and  many 
pieces  were  ground  to  powder  before  they  could  escape,  thus  wearing  out 
the  jaws  and  cheek  pieces,  and  consuming  unnecessarily  a  large  amount 
of  power.  The  widened  jaws  permit  the  stones  to  escape  as  soon  as  they 
are  broken,  thus  leaving  them  of  more  uniform  size,  making  less  dust, 
and  breaking  them  with  the  least  possible  expenditure  of  power. 

EDWARD  P.  NORTH. — Regarding  objections  made  to  certain  clauses 
in  the  paper  under  discussion,  it  may  be  said  that  the  roller  with  unequal 
sized  disks  was  not  advised  for  maintenance,  but  unless  it  was  so  guided 
that  the  larger  disks  always  followed  the  same  tracks  its  use  would  cause 
less  tendency  to  longitudinal  ruts  in  the  road  than  the  ordinary  traffic. 

The  advisability  of  surfacing  a  clay  road  with  hard  pan  must  depend 
greatly  on  the  character  of  the  hard  pan — a  clay  hard  pan  might  be  ob- 
jectionable. 

Messrs.  Spielman  &  Brush's  practice,  as  detailed  on  p.  119,  is  un- 
doubtedly sound  under  the  circumstances,  viz. :  an  absence  of  water  for 
•compacting  and  puddling,  but  a  better  road,  with  hss  tendency  to  inter- 
nal wear,  would  have  been  formed  by  a  steam  roller,  if  sufficient  water 
could  have  been  procured. 

Lavoinne  seems  to  have  misunderstood  the  effect  of  the  screenings, 
/.  <?.,  small  fragments  of  stone  from  the  breakers.  The  coarser  of  these 
are  applied  only  when  compacting  has  proceeded  so  far  that  the  stones  have 
a  tendency  to  roll  over  one  another  and  round  their  angles ;  these  screen- 
ings bind  the  stone  and  prevent  to  a  great  extent  further  wear.  About 
33  per  cent,  of  screenings  are  worked  into  the  metal  and  are  used  in  pudr 
dling.  Probably  about  25  per  cent,  of  this  is  coarse  screenings  in  the 
interstices  between  the  stones,  the  rest  being  fine  screenings  and  that 
used  in  puddling. 

Law  &  Clarke,  p.  145,  give  10  or  n  cubic  feet  interspace  per  yard — 40 
per  cent,  in  compacted  stone.  In  Paris,  about  24  per  cent,  of  sand  is  used 
in  binding,  and,  as  above  stated,  33  per  cent,  of  screenings  are  used  here. 

It  was  not  the  intention  to  argue  for  poorly  constructed  wooden  pave- 
ments, but  rather  to  show  the  practice  where  wood  pavements  are  suc- 
cessful, with  the  hope  that  it  might  be  followed  in  this  country.  The  fact 
that  wood  pavements  as  usually  constructed  here,  and  never  repaired,  have 


152  CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

proved  failures,  cannot  be  denied,  but  that  a  well  made  and  intelligently 
maintained  wood  pavement  would  be  a  failure  is  doubted. 

The  following  memorandum  from  Cleveland  confirms  this  view  :  "  In 
the  year  1873  5,070  square  yards  of  creosoted  wooden  pavement  were  laid 
in  Franklin  street,  Cleveland.  The  pine  blocks  were  creosoted  with  about 
4  pounds  of  oil  per  cubic  foot.  Since  that  time  no  money  has  been 
expended  in  maintenance,  and  the  pavement  is  in  excellent  order. 

"At  the  same  time,  and  in  the  same  street,  an  equal  area  was  laid  with 
blocks  prepared  by  the  '  Thilmany'  process;  of  this,  1,400  square  yards 
have  been  relaid  by  the  city." 

It  is  unfortunate  that  the  asphalte  pavements  in  Washington  were  so 
poorly  laid. 

I  street  has  such  an  excessive  crown  that  it  is  only  in  the  centre  of  the 
wheelway  that  the  street  is  sufficiently  flat  for  ease  or  comfort  in  driving. 

On  Pennsylvania  avenue  the  transverse  profile  is  good,  but  the  heated 
powder  was  apparently  laid  on  damp  concrete,  and  the  surface  is  badly 
cracked  in  consequence,  and  has  been  extensively  repaired,  though  it  was 
laid  in  the  fall  of  1877,  and  it  is  doubtful  if  it  wears  more  than  five  years 
in  all. 

In  Paris,  with  a  much  heavier  traffic,  asphalte  lasts  1 5  years. 

The  bituminous  mastic  pavements  described  by  Mr.  McComb  present 
very  fine  surfaces,  and,  if  they  wear  as  well  as  now  hoped,  will  have  all 
the  advantages  of  compressed  asphalte,  except  durability,  at  reduced  cost, 
and  their  use  may  be  advisable  in  streets  of  light  traffic. 

The  present  practice  is  to  make  the  wearing  surfaces  harder  than  has 
been  usual,  it  having  been  held  that  all  mastic  pavements,  subjected  to 
street  traffic,  should  be  made  so  soft  as  to  dent  in  summer,  to  prevent 
their  breaking  up  in  winter. 

The  weak  point  of  bituminous  mastics  seems  to  lie  in  the  expense 
necessary  to  free  the  Trinidad  bitumen  from  clay,  and  the  difficulty  of 
getting  sand  that  is  free  from  clay,  and  fine  enough  to  absorb  sufficient 
bitumen  for  cohesion  in  cold  weather,  without  an  excess  in  hot  weather, 
Loam  or  loamy  sand  was  used  at  first  to  enable  the  mixture  to  carry 
sufficient  bitumen  for  wear,  but  the  rapid  rotting  in  the  gutters,  and  at 
other  points  where  water  lies,  has  led  to  the  use  of  15  to  16  per  cent,  of 
limestone,  ground  to  pass  through  a  sieve  with  26  meshes  to  the  inch, 
which  probably  will  not  be  so  detrimental  to  the  mastic  as  clay. 

In  reply  to  a  question  as  to  the  amount  of  clay  allowed  in  mastic 
work  in  Europe,  M.  Leon  Malo  writes :  "  In  principle,  no  clay  at  all 
ought  to  be  in  mastic  ;  the  asphalte  rock,  being  quite  pure  limestone,  is 
desired  to  be  mixed  with  quite  pure  bitumen.  But,  in  reality,  the  bitu- 
men of  Trinidad  having  been  generally  adopted  in  works  by  want  of  pure 
mineral  bitumen,  and  as  it  is  impossible  to  quite  deprive  that  bitumen  of 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.     153 

its  clay,  it  is  admitted  that  the  clay  brought  into  the  asphalte  works  by  the 
Trinidad  bitumen  can  be  accepted  ;  that  is  to  say,  from  2  to  3  per  cent,  of 
clay  in  the  mastic.  For  the  compressed  asphalte,  to  which  no  bitumen  is 
added,  not  one  quantity  of  clay  is  allowed." 

Regarding  the  asphaltic  mastic  sidewalks  of  Paris,  it  should  be  noted 
that  there  is  always  a  temptation  on  the  part  of  the  mastic  workers  to  use 
too  much  bitumen,  as  the  larger  the  percentage  the  more  easily  the  mastic 
is  worked ;  and,  unless  it  is  kept  very  low,  the  pavement  will  dent  in  hot 
weather.  The  mud  must  have  been  brought  on  from  the  wheelways,  as, 
according  to  Chabrier,  the  mastic  sidewalks  under  the  arcades  of  the  Rue 
de  Rivoli,  Paris,  wore  about  half  an  inch  in  13  years — too  small  a  wear  to 
produce  much  mud. 

The  necessity  for  better  pavements  than  those  offered  by  the 
prevalent  granite  blocks,  will  justify  the  insertion  of  a  translation  from 
M.  Leon  Male's  "  Note  sur  L'Etat  Actuel  de  L  Industrie  de  L' Asphalte 
Parts,  1879." 

The  experiment  of  compressed  asphalte  for  carriageways  has  now  been 
made.  It  has  shown  its  defects  and  its  advantages ;  we  do  not  hesitate  to 
say  that  its  advantages  far  exceed  its  defects. 

We  do  not  now  speak  of  its  noiselessness  nor  of  its  precious  property 
of  creating  neither  dust  nor  mud  ;  of  its  agreeable  aspect  to  the  eye,  which 
is  a  quality  not  to  be  neglected  in  the  ensemble  of  the  embellishment  of  a 
city  ;  we  have  shown  the  importance  of  these  in  our  first  work.  We  insist 
only  on  its  action  upon  the  public  health  ;  a  point  which  we  did  not 
sufficiently  emphasize. 

The  asphalte,  placed  over  the  soil,  like  a  layer  of  caoutchouc,  abso- 
lutely intercepts  any  communication  between  the  soil  and  the  atmosphere  ; 
it  does  not  allow  rain  water,  which  runs  rapidly  into  the  sewers,  to  pene- 
trate ;  and  thanks  to  its  water-repelling  (•'  hydrofuge ")  character,  the 
carriageways  dry  as  soon  as  the  rain  has  ceased. 

A  stone  pavement,  on  the  contrary,  permits  a  constant  communica- 
tion between  the  soil  and  air  through  its  joints.  All  the  impurities  of  the 
surface,  dissolved  by  the  surface  waters,  are  by  them  carried  into  the 
earth ;  then,  when  the  sun  strikes  it,  these  impure  waters  are  evaporated, 
returning  miasma,  bred  below  the  pavement,  into  the  air ;  it  is  an  evil 
which  has  been  long  recognized  and  uncontested,  but  against  which  no 
remedy  is  known. 

The  system  of  joining  pavements  with  asphaltic  mastic  might,  per- 
haps, obviate  it,  but  it  is  very  costly,  and  renders  the  carriageway  ex- 
tremely hard  for  vehicles.  Compressed  asphalte  seems  to  have  solved  the 
problem  ;  and  we  are  compelled  to  think  that  of  all  the  services  which  it 
can  render,  this  is  the  most  efficacious  and  the  most  precious.  To  be 
sure,  the  influence  of  deleterious  miasmas  radiated  from  the  different  sys- 


154    CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 


terns  of  pavements  with  open  joints,  cannot  be  analyzed  in  a  precise 
manner ;  it  is  judged  rather  by  induction  than  by  a  direct  observation 
which  can  be  put  in  figures  ;  but  it  is  not  the  less  evident  and  not  the  less 
to  be  dreaded. 

M.  Malo  also  gives  the  following  tabulated  results  of  analysis  made  in 
the  laboratory  de  L'Ecole  des  Fonts  et  Chaussees  on  different  asphaltes: 


Val  de 
Travers. 

Seyssel. 

Lobsan. 

Sicilian. 

Maestu. 

Forens. 

Water  and   matter  volatile  at 
212°  Fl          

0.50 

1.90 

3.40 

0.80 

0.40 

0  25 

Bitumen 

10  10 

8  00 

11  902 

8  85 

8  80 

2  25 

Cabonate  of  lime  

8T.95 

89'  55 

69.00 

87.50 

9.15 

97  00 

Silicious  sand 

3  05 

0  60 

57.40 

Aluminum     and    peroxide   of 
iron 

0  25 

0  15 

5.703 

0.90 

4.35 

0  15 

Sulphur 

« 

5  00 

Carbonate  of  magnesia 

0.80 

0.10 

0.30 

0.95 

8.10 

0  20 

Different  minerals  insoluble  in 
acids        

0.45 

0.10 

«i 

11.35 

0.05 

Loss 

0  45 

0  20 

1  65 

0.40 

0  45 

0  10 

100.00 

100.00 

100.00 

100.00 

100.00 

100.00 

NOTES. 

1.  The  water  given  above  depends  on  the  dryness  of  the  sample  at  the 
time  of  analysis ;  the  figures  not  being  of  importance  in  the  result. 

2.  This  quantity  appeared  to  contain  a  certain  proportion  of  oil,  which 
was  mixed  with  the  bitumen  and  was  not  exactly  determined. 

3.  This  comprises  4.45  of  iron,  combined  with  sulphur. 

M.  Durand-Claye,  Director  of  the  laboratory,  speaking  of  the  Lobsan, 
says :  "  It  contains  about  g%  per  cent,  of  pyrites,  which  may  become  the 
cause  of  failure  in  employing  this  material.  The  heat  to  which  it  is  sub- 
mitted may  cause  it  to  lose  half  of  its  sulphur,  and  be  transformed  into 
protosulphate  of  iron,  an  oxydizable  material,  which  by  exposure  to  the  air 
is  transformed  into  a  soluble  sulphate  of  iron ;  disintegration  may  result 
from  this  a  short  time  after  putting  it  in  place." 

Mr.  H.  F.  Starr,  of  the  Columbia  College  School  of  Mines,  kindly 
made  an  analysis  of  some  Limmer  asphalte,  which  gave  the  following 
result : 

Bitumen...  .     8.26 

Clay 4.98 

Carbonate  of  lime 56.54 

.     Carbonate  of  magnesia ....27.01 

Sesqui-oxideofiron 8.21 

100.00 

This  is  the  only  analysis  I  have  seen  of  an  asphalte  that  will  not  com- 
press, and  the  only  one,  excepting  the  Maestu,  in  which  there  is  over  one 
per  cent,  of  carbonate  of  magnesia. 


CONSTRUCTION  AND  MAINTENANCE  OF  ROADS.    155 

M.  Malo  gives  analyses  of  seven  different  cargoes  of  crude  Trinidad 
bitumen.  In  each  case  the  samples  Were  thoroughly  dried,  losing  from  32 
to  38  per  cent.,  after  which  the  average  of  the  analysis  was  bitumen  $i>£» 
and  clay  48  X  per  cent.  The  greatest  percentage  of  bitumen  in  any  sample 
was  57.55,  and  the  least  45. 

In  addition  to  the  description  of  the  hydraulic  crusher  furnished  by  Mr. 
Martin,  a  mention  of  the  new  Blake  crusher  may  be  of  interest.  See  figure. 


In  it  the  old  cast-iron  frame  is  replaced  by  steel  rods  and  a  Wooden 
frame,  so  cushioned  that  the  fly-wheel,  in  case  of  abnormal  resistance, 
can  make  a  part  of  a  revolution.  The  pitman,  which  is  above  the  driving- 
axle,  can  be  lengthened  or  shortened,  so  as  to  increase  or  diminish  the 
stroke  of  the  jaws,  and  the  length  of  the  toggles  has  been  increased.  It  is 
probable  that  these  changes  will  reduce  the  expense  of  stone-breaking  by 
diminishing  the  breakage  account,  which,  particularly  with  trap  rock,  is  a 
serious  item. 

Mr.  J.  L.  Gillespie,  C.  E.,  gives  me  the  following  as  the  cost  of  break- 
ing 15,150  cubic  yards  of  limestone  during  1874-5-6-7,  for  the  concrete 
used  in  the  preservation  of  the  Falls  of  St.  Anthony.  The  machine,  an 
8-inch  by  1 6-inch,  old  pattern  Blake,  was  run  by  water  power,  for  which 
there  was  no  charge. 

The  cost  and  quantities  were  as  follows,  the  stone  being  delivered  at  the 
breaker : 

1874-5. . .  ...  8,452  cubic  vards  at, . .  . .  .41.     cefcts. 

18T5-6 ......8,284  ''  81.8      «* 

1876-7....    8,414  "  Ifc        " 


156     CONSTRUCTION  AND  MAINTENANCE  OF  ROADS. 

One  cubic  yard  of  stone  produced  about  two  cubic  yards  of  broken 
stone,  the  void  spaces  in  which  amounted  to  50  8-10  per  cent.  The  break- 
ages were  confined  to  some  rubber  springs,  one  back  block,  and  two  sets 
of  jaws  and  cheeks. 

The  cost  of  breaking  trap  on  the  Palisades  is  given  as  follows,  the 
stone  being  sledged,  to  go  into  the  jaws  readily. 

Two  crushers  deliver  35  cubic  yards  of  2-inch  stone  per  day,  when 
working  well ;  1 5  per  cent  of  the  time  is  lost  by  breakdowns. 

COST. 

1  engineman  and  fireman,  at  $2.50 $2.50 

2  laborers,  feeding 1.25 2.50 

2        "        screening l.V!5 2.50 

$7.50 

Coal,  1  ton 3.50 

Oil  and  waste 1.00 

Breakages 5 . 00 

$17.00 

or,  say,  57  cents  per  cubic  yard. 

On  Snake  Island  three  crushers  were  arranged  in  a  row,  and  the  broken 
stone  was  carried  by  an  endless  belt  to  the  revolving  screen,  whence  it  fell 
into  the  bins,  so  that  no  screeners  were  employed.  The  engine  had  one 
cylinder,  8  inches  by  24  inches,  and  was  running  with  80  pounds  of  steam. 
The  product  was  said  to  be  180  cubic  yards  per  day  when  there  was  no 
breakdown. 


1  engineman  and  fireman,  at  $2.50 $2.50 

8  laborers,  feeding 1.25 8,75 

$6.25 

2J  tons  of  coal,  at  $3.50 8.75 

Oil,  etc 2.00 

Breakages 15.00 

$32.00 

Allowing  for  the  i  $  per  cent,  lost  by  breakdowns,  the  cost  would  be 
about  21  cents  per  cubic  yard. 

At  another  place  on  the  Hudson,  two  crushers,  set  face  to  face,  9-inch 
by  1 5-inch  jaws,  could  deliver  at  the  rate  of  1 20  cubic  yards  per  day, 
when  no  trouble  occurred,  but  100  cubic  yards  was  a  fair  average. 

COST. 

Engineman  and  fireman ......  $2.50 

3  feeders 8.75 

2  screeners 2.50 

$8.75 

\\  tons  coal,  at  $4 6.00 

Oil,etc..... 2.25 

Repairs 10.00 

$27.00 

or  27  cents  per  cubic  yard. 

NOTE.— A  detailed  statement  of  the  cost,  in  time,  of  breaking  stone  is  given  in  the  Memoir  on 
the  Construction  of  a  Masonry  Dam,  by  J.  J.  R.  Croes.  Transactions  of  The  American  Society 
•of  Civil  Engineers,  No.  CHI.,  Vol.  VIII.,  page  856  (February,  1875).— [EDITOR.! 


AD  VERTISEMENTS. 


157 


AVELING   &   PORTER 

STEEL  STEAM  ROAD-ROLLER. 


The  Only  Successful  Steam  Road-Roller  ever  Built. 


Messrs.    Aveling   6°   Porter  were  Awarded  the  First  Prize   Gold 
Medal  at  the  Paris  Exposition,  1889. 


"BARNARD    CASTLE" 

Patent     Street     Sweeping     Machines, 

Street  Scrapers,  etc. 

6,000      BUILT. 


W.    C.    OASTLER, 

Consulting  Engineer  on  Jlighways, 
43  EXCHANGE  PLACE,  NEW  YORK  CITY, 


158  ARTICLES  ON  STREETS,  HIGHWA  YS  AND 

INDEX    TO    BEADING    ARTICLES 

ON 

Streets,    Highways    and    Paving    Materials, 

IN 
ENGINEERING  NEWS. 

NOTE  —This  index  refers  only  to  reading  articles  of 
greater  or  less  length  on  these  various  topics.  Much 
further  information  as  to  prices  paid  in  various  localities 
will  be  found  under  the  head  of  "News  of  the  Week." 
Numerals  refer  to  the  page  and  Roman  letters  to  volume. 


ASPHALTE: 

Val  de  Travers,  517,  viii. 

An  Ancient  Pavement,  191,  xiii. 

And  its  Application  to  Street  Paving,  by  E.  B.  Ellice- 
Clark,  Assoc.  Mem.  Inst.  C.  E.,  154,  202,  vii. 

Antiquity  of,  58,  xi. 

Pavements,  129,  xiii;  39,  44,  xix. 

New  York  Pavements,  169,  xxii. 

For  Paving,  291,  xxii;  28,  136,  150,  ix. 

Technical  Uses  for,  129,  xviii. 

And  Concrete  Paving,  473,  xxii. 

Effect  of,  on  Workmen,  47,  xiv. 

Deposits  of  California,  27,  xvii. 

French  Rock,  253,  xiii. 

Kentucky,  99,  xx. 

Italian,  242,  xiv. 

Roadways  of  Berlin,  Leon  Malo,  329,  346,  94,  xiii. 
Barber  Asphalt  Co.  vs.  James  Brand,  119,  xx. 
Beacon  st.,  Boston,  Improvement,  410,  xix. 
Berlin  Pavements,  261.  xix. 
Berlin  and  Paris  Pavements,  57,  xxii. 
Blast  Furnace  Slag  for  Paving  Blocks,  118,  xviii. 
BRICK  STREET  PAVEMENTS  : 

Brick  Street  Pavements,  90,  296,  320,  xvii;  330,  xiv;  99, 
593,  596,  601,  xxii. 

In  Bloomington,  111.,  552.  x. 

In  Toronto,  Can.,  17,  xviii. 

In  Berlin.  167,  31,  304,  xii. 

Boston  Street  Improvement.  West  End,  292,  xviii. 
HIGHWAYS: 

Country,  Apr.  28. 101,  iy. 

Construction  and  Maintenance  of  Public,  by  E.  B. 
Ellice-Clark,  C.  E.,  378,  382,  iii. 

Construction  and  Maintenance,  536,  xix. 

in  the  United  States,  9,  xix. 

Highway  Obstruction,  Decision  on,  454,  xix, 
House  and  Street  Drainage  of  Philadelphia,    Condensed 
from  a  papei   by  R.  Hering,  read  before  the  Engineers' 
Club  of  Philadelphia,  91,  v. 
PAVEMENTS: 

Asphaltum,  How  Made.  76,  xi. 

St.  Louis  Asphalt,  357,  572,  x. 

Asphalt,  463,  xx. 

New  Orleans  Asphalt,  491,  x. 

Brick,  94,  275,  471,  554,  588,  xxi. 

Cedar  Block,  282,  xxii.:  494,  xxi. 

Cedar  in  Toronto,  360,  ix. 

Creosoted  Wood,  427,  xxi. 

Composite.  149,  xi. 

Description  of  Granite  Block,  of  Providence,  R.  I.,  Laid 
in  1880,  45,  ix. 

Granite,  11,  xii. 

Specifications  for  Laying  Granite  Block  in  Washing- 
ton, D.  C.,  384,  v. 

Granite  in  London,  288,  xviii 

The  Grano-Melallic  Stone,  234,  xiv. 

The  Guidet,  107,  132,  ix. 

Impervious  Street,  138,  ix. 


PA  VING  MA  TE RIALS  IN  ENGINEERING  NE  WS.     1 59 

The  Kerr,  30,  xii. 

Movable,  479,  xx. 

Berlin  Wood,  34,  xx. 

Buda-Pesth,  275,  xxi. 

Here  and  Abroad,  186,  xiv. 

In  Detroit,  346,  xxii. 

Houston,  Tex.,  49,  110,  xxi. 

In  Kansas  City,  Mo.,  5i4,  xix. 

In  London,  295,  v . 

New  York  City,  588,  xxi. 

Pennsylvania  Avenue,  Washington,  323,  xxi. ;  272,  v. 

The  Pelletier,  51,  ix. 

Suit  in  Pittsburgh,  357,  xxi. 

In  Philadelphia,  311,  xix. ;  299,  xxi. 

Cost  of  Wood  in  St.  Louis,  102,  xiii. 

Of  American  Cities,  322,  xxii. 

In  Washington,  D.  C  ,  323,  xx. 

Relative  Merits  of,  475,  xix. 

Macadam,  St.  Louis,  Mo.,  216,  xxi. 

Macadam  vs.  Cedar  Block,  416,  vii. 

And  Paving,  93,  592,  xxi. 

Law,  Pennsylvania,  395,  xxi. 

Foreign  Practice  in,  317,  xviii. 

Los  Angeles  Cement,  362,  xxii. 

Effect  of  Heat  on  Cement,  17,  xviii. 

Our  City,  223,  xviii. 

Cost  of,  in  N.  Y.,  xiv 

A  New,  161.  v. 

Street  Pavements,  Dec.  1,  337,  iv.  An  exhaustive  re- 
view of  the  subject  by  Mr.  Robt.  Moore,  C.  E.,  St. 
Louis,  before  the  University  Club.  Faults  and  ex- 
cellencies of  the  various  systems,  with  estimates  of 
the  respective  cost  of  each.  May  6,  etc.,  146, 163,  170, 

Abstract  of  an  article  by  Gen.  Q.  A.  Gilmore  in  the 

N.  Y.  Tribune,  Feb.  19,  57,  iii. 
Past,  Present  and  Future,  a  paper  by  Jno.  H.  Sarcrent, 

Read  before  the  Cleveland  Club  of  Engineers,  xviii. 
An  extract  from  a  report  of  F.  Shanly,  City  Engineer, 

Toronto,  Ont.,  iii. 
In  Chicago,  224,  xviii. 
In  St.  Louis,  by  Thos.  K.  Mackland,  before  Soc.  of 

C.  E.,Feb.  18, '85,  355,  xiii. 
For  Heavy  Traffic,  257,  v. 
Of  Paris.    Translated  for  Inst.  C.  E.,  by  D.  K.  Clark, 

Oct.  17,  334,  v. 

In  East  Saginaw,  Mich.,  3,  xviii. 
In  Paris,  Report  by  the  Chief  of  Roads  and  Streets 

191,  v. 

Of  Washington,  D.  C.,  Annual  Report  on,  297,  xviii. 
Of  San  Francisco,  321,  ix. 
In  Chicago,  Cincinnati,    Philadelphia  and  Baltimore, 

How  Paid  for,  132,  xiii. 
Of  Kansas  City.    W.  B.  Knight.    Paper  before  C.  E. 

Club,  Nov.  29,  285,  xii. 
Philadelphia,  168,  271,  xiv. ;  217,  xix. 
In  Plainfield,  N.  J.,  15,  xvii. 
PAVING: 

Brick  for  Street,  xx. 
"Iron"  Brick  for,  395,  xxi. 
A  New  Material  for,  257,  xiv. 
Road  Metal  and  Setts  in,  224,  xx. 
Specifications,  Houston,  Tex.,  396,  xxi. 
Pitch  Lake.    Trinidad,  501,  xxi. 

Report  of  Board  of  Experts  on  Street  Paving,  in  Philadel- 
phia, xii. 

Paving  Blocks,  Buda-Pesth,  494,  xix. 
Paving  Bricks,  Bitumen,  203,  xxi. 
Race  Track  Construction,  by  Chas.  Holmes,  E.  Saginaw 

Mich.,  242,  259,266,  vi. 
ROADS: 

Cost  of  Bad,  102,  xiii. 
Value  of  Good,  449,  xxi. 
Common,  36,  iii. 
Good  County,  89,  xiii. 


160  ARTICLES  ON  STREETS,  HIGHWA  YS  AND 

Our  Country,  236,  269,  xvii. 

Gravel,  Senator  Washburn  on,  487,  xix. 

And  Road -Making,  by  W.  B.  Sears,  Ch.  Eng.  F.  &  P. 

M.  R.  R.,  85,  xi. 

Making  and  Repairing,  314,  xiv. 
Building,  381,  xxi. 

Legislation  for  the  American  ;  tate,  203,  538,  xxii. 
Specifications  for  Laying  Macadam,  364,  v. 
Macadam's  Improvements  in  Making,  80,  x. 
Width  of,  186,  xxii. 

The  Construction  and  Maintenance  of,  by  E.  P.  North, 
C.  E.,  read  before  Am.  Soc.  C.  E.,  April  16,  1879, 
228,  235,  243. 
Rollers,  251,  vl. 
The   Construction   and   Maintenance   of   Public,    an 

English  blue  book,  223,  ix. 

Construction  and  Maintenance  of  French,  139,  xxi. 
Construction  and  Repair  of,  324,  xxi. 
And  .bridges  in  Georgia,  132,  101,  xiii. 
Convict  Labor  in  Georgia,  134,  444,  xxi. 
Cost  of  Grading,  in  Minnesota,  271,  xiv. 
Resolution  of  Illinois  Highway  Commrs.,  327,  xix. 
French,  160, 183,  xxi. 
Illinois  Laws  relating  to,  310,  x, 
Making,  in  China,  6,  xix. 
Law  in  Georgia,  329,  xxi. 
In  Illinois,  487,  xix. 
In  Illinois,  Condition  of,  145,  xxii. 
In  Long  Island,  Macadam,  529,  xxii. 
In  Massachusetts,  25,  xxi. 
In  Virginia,  by  D.  H.  King,  340,  v. 
Improvements  of,  in  Massachusetts,  317,  xxi. 
New  Jersey,  77,  512,  xxii. 
Improvement  of,  in  New  York,  373,  xix. 
In  Pennsylvania,  25,  289,  305.  xxi. 

Public,  Their  Construction  and  Repair:  Seven  Ques- 
tions by  a  Louisiana  County  Surveyor,  13,  iii. 
Improvement  of  Prairie  and  Streets,  by  T .  J.  Nicholl, 
C.  E.,  read  before  C.  E.  Club  of  N.  W.,  Sept.  3,  1878, 
310,  v. 

Making  Prairie,  193,  v. 

Private  Roadways  and  Streets  in  England,  407,  xiv. 
Michigan  Ave.,  Chicago,  Improvement  of,  367,  vii. 
Riverside  Avenue,  N.  Y.  City,  Improvement  of,  Speci- 
fications, 326,  334,  342,  iv. 
Road  Roller,  Aveling  &  Porter,  221,  xxii. 
Road  Making,  The  Science  of,    by   Clemens    Herschel, 
a  First   Prize  Treatise  awarded    by  the    Mass.  State 
Board  of  Agriculture,  148,  156,  164,  169, 176, 185,  194,  202, 
213,  221,  229,  235,  iv. 
ROAD: 

Pike's  Peak  Wagon,  152.  xx. 
Law  in  Roanoke,  Va.,  110,  xxi. 
Bills,  Penna..  299,  xxi. 
Specifications  for  Plank,  437,  xxi. 
Shell,  in  Louisiana,  423,  xix. 
STREET  CLEANING: 

Street  Cleaning,  77,  v 

Of  Paris.    Translation  by  L.  Soulerin  from  the  French 
of  M.  "Vaissiere,  Ch.  Engr.  Roads  &  Bridges,  and 
read  before  C.  E.  Club  of  N.  W.,  June  18,  215,  v. 
In  Paris,  238,  viii;  94,  xvii. 
Bill  for  N.  V.  City,  246,  247,  viii. 
And  Maintenance,  75,  xiv. 
In  New  York,  409,  xiv. 
And  Garbage  Removal  in  N.  Y.,  394,  xiii. 
English  Street  Cleaning  Items,  280,  xiii. 
In  Montreal,  57,  vi. 
In  Vienna,  285,  xix. 
STREET  SWEEPING; 

Street  -Sweeper,  179,  210,  xviii. 
Street  Sweeping,  476,  xxi. 
In  London,  151,  iv. 
In  Buffalo,  269,  xviii. 
In  St.  Paul,  161,  xiv. 


PA  VING  MA  TERIALS  IN  ENGINEERING  NEWS.     161 

STREET: 

Excavations  in  Washington,  D.  CM  410.  xxii. 

European  House-Building  and,  408,  xix. 

Lights,  Providence,  R.  I.,  305,  xvii. 

Refuse  Disposal  in  London,  '271  xvii. 

Sprinkling,  Bournemouth,  Eng.,  285,  xix. 

Sprinkling,  21,  436,  497,  xxi. 

Naming,  249,  2oO,  xix. 

Names,  London,  506,  xix. 

Naming  in  Mexico,  New  Method  of,  44,  xx. 

Renumbering  City,  105,  115,  viii. 

Maintenance  in  N.  Y,  City,  456,  xviii. 

Maintenance  in  Paris,  13,  xvii. 

Monuments,  4,  xvii. 

Grade  Intersections.  134,  150,  xvii. 

Sign,  70,  xvii. 

Commissioners,  Boston,  308,  xxi. 

Snow  Removal  in  Paris,  17a,  xvii. 

Act,  Penna.  Borough.  395,  xxi. 

Crossings,    Law  of  Over  and  Under  Grade,  327,  xix. 

Railway  Accidents,  184,  xix. 

Tramways,  by  Robinson  Souttar,  from  Proceed- 
ing Institution  Civil  Engineers,  304,  312,  iv;  322,  329 
339,  346,  iv. 

Curb  and  Gutter,  Philadelphia,  38,  xvii. 

Work,  Decision  on,  327,  xix. 

Bill,  Ives,  516,  xxi. 

Street  Refuse  in  Glasgow.  Disposal  of,  97,  xii. 
Street  Rails  and  Pavements,  80,  xix. 
STREETS: 

Resistance  to  Traction  in,  106,  ix. 

Length  of  London,  11,  xii. 
Street  Improvement,  Elm  St.,  N.  Y  ,  134,  xxi. 
Street  Improvement,  Laws  for,  in  Cities,  71,  iii. 
Streets,  The  Fee  of,  366,  ix. 
Streets.  Olden  Time,  24,  xx. 
Street  Paving,  256,  265, 350,  vii. 
Street  Paving,  Special   Assessments  for,  Court  Decision 

Sustained,  101,  xiii. 

Street  Paving  Specifications,  159,  227,  ix. 
Specifications  of  Western  Ave.  Improvement,  Albany,  N. 

Y.,  Mar.  10,  63,  iv. 

Sidewalk,  Repairing  of,  in  Washington,  D.  C.,  309,  ix. 
Subways  and  London  Streets,  285,  ix. 
Steam  Rolling  for  the  Maintenance  of    Roads    in    the 

Ardennes,  Annales  des  fonts  et  Chaussees,  447,  ix. 
Sheet  Asphalt  Paving,  102,  xifi. 
Slag  Paving  Blocks,  302,  xiii. 

The  Saddler  Brick  Pavement  for  Streets,  Col.  Flad's  opin- 
ion of,  587,  x. 

Tar  Concrete  Sidewalk,  539,  xxii. 
Tar  and  Gravel  Concrete  Street  Gutters,  130,  iv. 
Telford  Macadam,  221,  xxii. 
Turnpikes  in  Lancaster  Co.,  Pa.,  256,  xiii. 
Turnpiking  and  Underdraining  Common  Roads, by  R.  C. 

Carpenter,  C.  E.,  Lansing,  Mich.,  300,  306,  iv. 
Wear  of  Horse  Shoes  on  Macadam,  28,  viii. 
WOOD  PAVEMENTS  : 

Of  Chicago,  by  E.  A.  Fox,  C  E.,  a  Paper  read  before 
the  C.  E.  Club  of  N.  W.,  Jan.  2,  1878, 14,  22,  v. 

Of  Chicago,  287,  iv. 

In  the  Metropolis  of  London,  by  Geo.  Henry  Stay  ton, 
Proceedings  Inst.'C.  E.,  242,  253,  265,  277;  7,  xii. 

In  Berlin,  156,  xi. 

In  Paris,  462,  552,  x 

In  London,  531,  580,  x. 

Wood  as  a  Paving  Material  under  Heavy  Traffic.  O. 
H.  Howarth,  Assoc.  Inst.  C.  E.  Proceedings  Inst. 
C.  E.,  212,  vi. 

Wood,  Treatment  of,  for  Street  Pavements,  by  Thos. 
J.  Caldwell  and  Thos.  D.  Miller,  before  St.  Louis 
Club  of  Engineers,  March  4,  1885.  322,  xiii. 

Wood  vs.  Stone  Pavements,  193,  xii. 

Wood  Pavement  in  Dalla-,,  Tex.,  Specifications  for 
Bois  D'Arc,  178.  x. 


162 


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FOB   SALE  BY 

ENGINEERING  NEWS  PUBLISHING  CO, 


TRINIDAD      JSPHALT 

Sheet     Cements 


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And  in  each  City  there  is  an   Urgent  Demand  for  More  of  It. 


This  Pavement  is  laid  with  GENUINE  TRINIDAD  ASPHALT,  without  ad- 
mixture  of  Coal  Tar  or  any  of  its  products.  It  GREATLY  ENHANCES  the 
VALUE  OF  REAL  ESTATE,  and  has  MORE  POINTS  OF  MERIT  AND  FEWER 
DEFECTS  THAN  ANY  OTHER  PAVEMENT. 

DURABILITY    GUARANTEED. 


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